As technological advances provide opportunities for handicapped individuals to experience the world in ways that were previously impossible, poskim grapple with these developments and try to determine how they integrate into the world of halacha.  One area that has produced a large literature is artificial organs. Are these devices viewed as regular biological organs or not? We will explore how artificial devices such as hearing aids and cochlear implants that enable the hard of hearing and the deaf to hear, are treated halachically.

We will first describe the different mechanisms that hearing aids and cochlear implants use to enable hearing, then we will explore how these devices affect the status of a deaf individual and his obligation in mitzvot, and finally we will examine how they affect his ability to fulfill individual mitzvot that require hearing such as listening to the Megillah on Purim and hearing the Shofar on Rosh Hashana.

The Physiology of Hearing

One of the fascinating things about our sense of hearing is that the entire range and diversity of sounds we can hear, from the soft din of a fluorescent light, to a conversation with a friend, to the painful screeching of a subway into the station are all processed by the same biological machinery. All these events generate different patterns of sound waves that travel through the air and into our ears where they are transformed into electrical signals that are processed in our brain. All sounds are composed of waves of different frequencies and amplitudes. While a pure tone may be a single wave, a speaking voice is a complex amalgam of different frequencies. A complex and precise chain of events must occur in our ear and brain so that we can hear and decipher individual sounds.

When a sound wave hits our ears, it travels down the ear canal and arrives at the eardrum, the Tympanic Membrane - a thin membrane at the end the ear canal that vibrates when a sound wave strikes. The other side of the eardrum is connected to a series of three tiny bones known as the Ossicles that vibrate in a complex manner to amplify the sound.  These vibrations ultimately cause another membrane, the Oval Window, covering a small aperture at the entrance to a larger structure, the Cochlea, to vibrate. It is in the Cochlea where this complex pattern of vibrations is separated into its basic parts and transformed into electrical signals that travel to the brain where they are processed and recognized as individual sounds.

The cartoon diagram llustrates the different components of the ear.  Sound waves travel through the outer ear and down the ear canal. They cause vibrations in the Tympanic Membrane which in turn causes movements in the Ossicles and finally undulations in the fluid contained inside the cochlea.

The Cochlea is a coiled tube about the size of a chickpea filled with a fluid that undulates at different frequencies as the Oval Window vibrates. Another thin membrane, the Basilar Membrane, is covered by some 30,000 tiny hair cells and runs along the inner length of the cochlea, covering the fluid. These hair cells are themselves connected to nerve fibers that can send electric messages up to the brain. As waves are generated in this fluid, the Basilar Membrane moves in rhythm with the fluid and physically stretches these hair cells, which then tug on the nerve fibers, causing them to send an electrical signal up to the brain.

When sound waves enter the ear, the Basilar membrane is able to break sounds down to their component parts due to its non-uniform structure. While one end of the Basilar membrane is wide the other end tapers; the tapered base is taut and sturdy while the apex is wide and floppy.  These two features prevent the entire membrane from constantly vibrating any time waves pass through the fluid. Instead, sections of the Basilar membrane vibrate independently from other regions in response to the motions in the fluid, enabling different portions to be sensitive to different frequencies. Specifically, low sounds cause vibrations at the wide and floppy end of the Basilar Membrane, while high sounds stimulate the narrow and sturdy end. Only hair cells at the particular region of the Basilar Membrane that is vibrating will be stretched and they will send signals up the nerve fibers where the brain can assemble and identify the different sounds.

Many hard of hearing and deaf people have impairments in these hair cells and thus are unable to transform the waves in the fluid into an electrical impulse to communicate with the brain, preventing them from experiencing sound. There are two primary methods that attempt to compensate for these impairments: hearing aids and cochlear implants, each of which uses a different mechanism to generate the sensation of sound.

Hearing aids amplify sound and function like a mini-microphone and speaker by generating an amplified version of the original sound. A microphone is situated adjacent to the ear where it collects sounds that enter the ear. These sounds are converted into electrical signals which are amplified and converted back into a louder sound emitted inside the ear in an attempt to stimulate whatever hair cells remain.

Cochlear implants, on the other hand, bypass the hair cells entirely and directly stimulate the appropriate nerve fibers.  To accomplish this, a thin electrode is wound into the cochlea and placed adjacent to the nerve fibers that are normally stimulated by the hair cells. This electrode acts like the hairs on the Basilar Membrane and is able to appropriately stimulate the different nerve fibers along the entire length of the cochlea depending on the frequencies of various sounds. The individual wears a small microphone and processor behind his ear, which collects sounds, digitally separates them into their component frequencies, and sends an electric signal to the surgically implanted electrode which stimulates the appropriate nerve fibers, thus generating the sensation of sound in the brain. Unlike a hearing aid, which uses a microphone to generate a new sound in the ear of the person, the cochlear implant uses a microphone to directly stimulate the appropriate nerve fibers without ever generating another sound in the interim.

Status of a deaf person and early deaf education

Of the five senses, the sense of hearing is unique in that one who is born without hearing is not only missing one of the five senses, but is unable to sense language itself. Oliver Sacks in his Seeing Voices, observes that

the prelingually deaf, unable to hear their parents, risk being severely retarded, if not permanently defective, in their grasp of language unless early and effective measures are taken.  And to be defective in language, for a human being, is one of the most desperate of calamities, for it is only through language that we enter fully into our human estate and culture, communicate freely with our fellows, acquire and share information (Sacks, p.8).

The world we live in converses using audible voices. Without the ability to hear and learn a language one will not only be cut off from society but from himself as well.  Not only will he be unable to develop a self awareness and articulate an identity, but it will be impossible to interact and integrate into society.

Historically, due to the inability to communicate with the deaf, people assumed that there was a fundamental deficiency in the mind of the deaf which could not be overcome and deaf individuals were treated as outcasts and left isolated from society. Only in the mid-18^th century, with the emergence of the first school specifically for the deaf, did the world begin to realize that with sign language, we could educate the deaf so they could develop into fully communicating participants in society. While this understanding was gaining traction, however, there were contentious debates as to whether the mind of deaf individuals was damaged making it impossible for them to learn to communicate and integrate into society, or whether they have the potential, but are simply missing the education to bring it to reality.

This debate is reflected as well in the development of the halacha's categorization of the deaf (חרש). Halachically, there are two different categories of the deaf: one that can speak but not hear and one that can neither hear nor speak (תרומות א:ב).  Rashi explains that the first class includes those who are postlingually deaf, people who were born hearing and developed the ability to communicate but later became deaf.

מדברת ואינה שומעת - כבר שמעה ולמדה לדבר ואחר כן נתחרשה (רש"י מסכת נדה דף יג עמוד ב).

One who speaks but cannot hear has already heard and learned to speak and only afterwards became deaf (Rashi, Nida 13b).

The second class includes those who are prelingually deaf, and never learned to communicate. Having never developed the ability to communicate, this deaf individual is classified with the imbecile and child, all three of which are considered not to have or exhibit any דעת - a particular level of mental awareness and an ability to interact and integrate into society. The Gemara in Chagiga explains,

מה שוטה וקטן - דלאו בני דעה, אף חרש - דלאו בר דעה הוא (תלמוד בבלי מסכת חגיגה דף ב עמוד ב).

Just like an imbecile and a child do not have daat so too a deaf person does not have daat (Chagiga 2b).

Postlingually deaf individuals are considered hearing for all purposes and are obligated in Mitzvot in general while someone who is prelingually deaf is not obligated in Mitzvot and has a similar status to an imbecile or child (משנה תורה הלכות אשות ב:כו).

Theoretically, one could imagine that there are two different ways that a prelingually deaf individual can overcome his deficiency and become obligated in Mitzvot: either through education that would enable him to demonstrate that he has דעת, or by giving him the sense of hearing.

In the mid-19^th century as deaf education was spreading around the world, there was a debate among the poskim as to whether or not the halachic status of the deaf could change via education. On the one hand there is precedent in the halacha that one who is born deaf has no דעת, yet the present reality demonstrated otherwise. The מהר"ם שיק writing in the mid-19^th century recognizes the presence of deaf education and schools, but is unsure whether or not after this education they achieve any kind of creative, clarity of mind. He writes that

ועכ"פ נראה דחרש שהורגל לדבר בבית חינוך עדיין לא יצא מידי ספק אינו בר דיעה לכל הפחות ואין לצרפו למנין ולהניח להוציא עצמו ע"י חרש כזה. (שו"ת מהר"ם שיק אה"ע ס' עט)

In any event it seems that regarding a deaf person who has become accustomed to speaking by virtue of education, it is still at least doubtful whether he is no longer considered someone who does not have daat, and should not be included in a quorum for prayer, nor should one allow the deaf person to exempt his obligation (Responsa of Maharam Shick, Even HaEzer 79).

Since he is unsure, he concludes by erring on the side of caution and believes that they are still considered exempt from Mitzvot.

In 1886, Rav Hildesheimer discusses in a responsum whether or not there is a fundamental deficiency in the mind of a prelingually deaf person or whether they have the mental capacity like everyone else, but it is simply "trapped" and they need the education to reveal it.

ונלע"ד שעיקר הדבר תלוי בשאלה אם כח השכל של החרש לקוי באופן מוחלט או שהוא נורמאלי כשלעצמו וכעין אוצר גנוז (שו"ת רבי עזריאל הילדסהיימר חלק ב - אבן העזר, חושן משפט ומילואים סימן נח)

It seems in my humble opinion that the crux of the issue depends on the question of whether the intellect of the deaf person is fundamentally impaired or it is actually normal, just like a hidden treasure. (Responsa of R' Azriel Hildesheimer, 2:58)

Based on conversations with principals of deaf schools who unequivocally affirm that a deaf child can be educated to the fullest ability and that their mind is as sharp and clear as any one else, he disagrees with the מהר"ם שיק and concludes by explaining that our understanding of the deaf does not contradict chazal who exempt them from Mitzvot due to their deficiency in דעת because chazal were dealing with someone who could not be educated.

וחזינן דהמציאות מכחשת את מש"כ הגאון מהר"ם שיק שפעולת החרש שלימדוהו הוי כמעשה קוף בעלמא ושאינה אלא כפי מה שנקבע ונטבע בו מההרגל והלימוד ואין לו בחירה ודעה חפשית...אבל כך היתה השקפת העולם ע"ד החרשים בזמנם וכן מבואר בספרי הרופאים מן התקופה ההיא, ורק לאח"כ נשתנתה דעתם עד שהגיעו למסקנא שיש לחרשים כח השכל (אלא שקשה להוציאו מכח אל הפועל), וכך הוכח בימינו בבירור מן הנסיון. ואין בזה שום סתירה לדחז"ל שלא דיברו אלא בחרש שלא היה באפשרותו להפעיל את כח השכל שלו. (שו"ת רבי עזריאל הילדסהיימר חלק ב - אבן העזר, חושן משפט ומילואים סימן נח)

We can see that the reality contradicts that which the Maharam Schick wrote that the actions of an educated deaf person are like the actions of a monkey and his actions are only the result of what he has been trained to do and he has no freedom or free will...But this was the view of the world regarding the deaf during their time, and so it was explained in the medical books during that time, and only afterwards did their opinions change until they concluded that the deaf have intellect (even though its difficult to bring into reality) and similarly it is proven in our days.  This is not a contradiction to chazal who were only discussing a deaf person whose intellect couldn't be brought to reality. (Responsa of R' Azriel Hildesheimer, 2:58)

Modern day poskim also side with Rav Hildesheimer based on the fact that through education, the deaf are fully functional and able to communicate and participate in society, and thus should be obligated in mitzvot.

Stimulating the sense of hearing

A second way that a prelingually deaf person could theoretically become obligated in Mitzvot is by gaining the sense of hearing. One of the earliest sources on the transformation from deaf to hearing is found in the פרי חדש.  Writing in the 17^th century, the פרי חדש discusses someone who can only hear through an ear trumpet, a funnel shaped object that collects sound and directs it towards the ear. He writes,

ומסתברא נמי דאף שאינו שומע כשמדברים עמו בקול רם זולת ע"י מין חצוצרות וכיוצא דלא מקרי חרש (פרי חדש אה"ע קכא:ו)

It makes sense that even one who cannot hear when you speak with him in a loud voice except by using an ear trumpet or other similar device is not called a deaf person (Pri Chadash Even HaEzer 121:6).

He believes that in this case he is a full-fledged hearing person, obligating him to fulfill mitzvot like any other adult.

This precedent set by the Pri Chadash is the basis for the discussion among the modern day poskim regarding hearing aids. Rav Ovadia Yosef and Rav Moshe Feinstein, in discussing how a hearing aid affects the status of a deaf person both use this פרי חדש as their starting point, but while Rav Ovadia expands this precedent, Rav Moshe limits it.  Rav Ovadia (יביע אומר ז:יח) explains based on this פרי חדש, that someone who hears with the assistance of an electric hearing aid is considered a hearing person and is obligated in Mitzvot and is able to exempt others of their obligation as well.

ומכאן יש ללמוד למי שאינו יכול לשמוע אלא על ידי מכונת שמיעה חשמלית, שאין דינו כחרש, ורשאי לקרות המגילה ולתקוע בשופר להוציא את הרבים ידי חובתם (שו"ת יביע אומר אורח חיים ז:יח).

From here you can learn that one who can only hear through an electronic hearing aid does not have the status of a deaf person, and is permitted to read the Megillah and blow the Shofar to exempt others of their obligation (Yabia Omer, Orach Chaim 7:18)

Rav Moshe Feinstein takes a different approach.  He differentiates between the expression of דעת and the ability to hear. Since a prelingually deaf individual who uses a hearing aid can communicate with others and integrate into society, his status becomes like a postlingually deaf individual and is obligated in mitzvot, independent of his ability to hear.

הנכון לע"ד דיש לו דין מדבר ואינו שומע שהוא כפקח... כיון שאין זה קלקול גדול במוח לכן אם היה מדבר שהיה שייך שיהיה לו התחברות עם בנ"א היה משלים הקלקול והחסרון שנעשה לו בדעתו (שו"ת אגרות משה אבן העזר חלק ג סימן לג).

The correct position it seems to me is that he has the status as one who can speak but not hear who is like a normal person...Since this is not a large deficiency in his mind, therefore if he speaks and can interact with people he has completed the deficiency in his mind (Igrot Moshe Even HaEzer, 3:33).

However, Rav Moshe doesn't go as far as Rav Ovadia and say he is a full fledged hearing person. He explains that although the פרי חדש believes that someone who hears through an ear trumpet is a hearing person, that doesn't extend to hearing aids. The difference between someone who uses an ear trumpet and someone who uses hearing aids is that with an ear trumpet, a person is still using their own ears to hear an original sound, the ear trumpet simply amplifies that sound. A person who can only hear using hearing aids, is using a machine to hear an electrically generated sound but cannot hear original sounds himself.

אבל לא מסתבר להחשיבו שומע כהא דשמיעה כשמדברים לו בקול רם וכהא דשמיעה ע"י חצוצרה...ולכן גם מי שאינו שומע אלא ע"י מכונה כיון שאינו שומע בעצמו אין להחשיבו לשומע, ול"ד לשומע כשמדברין בקול רם דהוא ודאי בחשיבות שומע, דאיכות השמיעה אינו שוה לכל אדם...ובשמיעה ע"י חצוצרה כיון שהוא דבר המצוי וגם שהשמיעה ע"י זה אינו דבר מחודש אלא מחמת שמתייחד הדבור רק לאזנו סובר הפר"ח דג"כ הוא בכלל טבעיות השמיעה, מאחר שלא כל אדם שוין ואיך ששומע נחשב שומע אפילו בא בקושי גדול, אבל מכונה ע"י עלעקטרי שהוא שמיעה דכח מחדש אין להחשיבו לשומע מאחר דאינו שומע כלל בעצם (שו"ת אגרות משה אבן העזר חלק ג סימן לג).

However, it does not make sense to consider this person, hearing, like one who can hear when you speak to him in a loud voice or through an ear trumpet...Therefore, one who can only hear through a machine since he cannot hear on his own, he is not considered hearing, and he is not like one who can hear when you speak in a loud voice for he is certainly considered hearing, since the quality of hearing is not the same for each person...And regarding hearing through an ear trumpet, since it is something common and that hearing through this is not something new, but since it focuses the speech only to his hear, the Pri Chadash believes that this too is included in natural hearing, since not everyone is the same and however you can hear is considered hearing if it comes through great difficulty, however, an electronic hearing aid that is listening using a novel source is not considered hearing since he fundamentally cannot hear (Igrot Moshe Even HaEzer, 3:33).

Rav Moshe expands this idea and explains that halacha in general only incorporates things that we experience through our natural senses without any machines.

דפשוט שכל עניני התורה נידונין כפי שרואין ושומעין בעצם לא ע"י מכונות וכדומה, וכמו שרצים שלא נראו לעין אלא ע"י דבר המגדיל שאינו כלום דהא כל האויר שאדם שואף לתוכו הוא מלא משרצים כאלו...ואין שום איסור בזה, וכמו כן מה שנראה הפסק באות בתפילין ומזוזות ע"י ספאקטיווע ולא נראה לעין בעצמו לא נחשב הפסק וכשר, וכדומה הוא בהרבה ענינים (שו"ת אגרות משה אבן העזר חלק ג סימן לג).

It is clear that all the areas of the Torah are judged based on how we can essentially hear and see without machines and the like. Just like bugs that are only visible through something that magnifies are nothing [in the eyes of the Torah] since all the air a person breathes in is full of microscopic bugs like these...and there is no prohibition with this, and similarly, what appears to be a break in a letter in Tefillin or Mezuzot when looking through a microscope, but is not visible to the naked eye, is not considered a break but is permitted, and similarly in many areas (Igrot Moshe Even HaEzer, 3:33).

Thus, although hearing sound through an ear trumpet is considered natural, hearing through hearing aids is not, since hearing aids enable hearing by synthesizing a novel sound that Rav Moshe considers qualitatively different from the original sound.

Although both Rav Moshe and Rav Ovadia agree that you have the status of a hearing person if you can only hear through an ear trumpet, they disagree as to the rationale and that affects whether hearing through a hearing aid transforms your status to a hearing person.  Rav Ovadia understands from these sources that anything that enables you to experience the sensation of hearing sound is enough for you to be considered a hearing person, while Rav Moshe focuses less on whether the individual can experience hearing and more on the mechanism that enables you to hear.

Fulfilling Mitzvat Shofar and Reading the Megillah

After discussing the status of deaf individuals and how artificial devices affect their status vis a vis Mitzvot in general, we will now explore the level of hearing required to fulfill specific Mitzvot where sound is an essential part of the mitzvah.  For example, in order to fulfill the mitzvah of listening to Megillat Esther on Purim or hearing the Shofar blown on Rosh Hashana, does one need to hear these events solely using their natural auditory capacity, or can one fulfill these Mitzvot experiencing the sound via an artificial device like a hearing aid or cochlear implant?

In describing the basic requirements of these Mitzvot, the Mishna prohibits one who cannot hear from exempting others of their obligation in these Mitzvot. The Mishna in Rosh Hashana (29a) while teaching that a deaf person cannot blow the Shofar to exempt others of their obligation, explains that someone who is not obligated in a Mitzvah cannot help others fulfill their obligation.

חרש שוטה וקטן אין מוציאין את הרבים ידי חובתן. זה הכלל: כל שאינו מחוייב בדבר - אינו מוציא את הרבים ידי חובתן. (תלמוד בבלי מסכת ראש השנה דף כט עמוד א).

One who is deaf, an imbecile, and a child cannot exempt others of their obligation. This is the general rule, anyone who is not obligated in something, cannot exempt others of their obligation. (Rosh Hashana 29a).

Similarly the Mishna in Megillah (19b) prohibits a deaf person from reading the Megillah to exempt others of their obligation.

הכל כשרין לקרות את המגילה חוץ מחרש שוטה וקטן (תלמוד בבלי מסכת מגילה דף יט עמוד ב).

Everyone is suitable to read the Megillah except one who is deaf, )an imbecile or a child (Megillah 19b).

What emerges from the ensuing Gemara is that the problem does not have to do with his status as a deaf person but simply that he cannot hear the Megillah and thus he is not obligated in this Mitzvah and cannot exempt others.

Although it is clear that one who cannot hear is not obligated in these Mitzvot, it is unclear what happens when someone can hear using non-natural means.  Regarding the use of hearing aids for these Mitzvot, there are three main opinions. R' Shlomo Zalman Auerbach believes that you cannot fulfill either of these Mitzvot through hearing aids, R' Ovadia Yosef thinks you do fulfill these Mitzvot with hearing aids, and R' Tzvi Pesach Frank distinguishes between these two Mitzvot.

In discussing whether you can fulfill the Mitzvah of Shofar or Megillah by listening through a microphone, R' Shlomo Zalman Auerbach explains that to fulfill these Mitzvot one must hear the original sound generated by the Shofar or the one reading the Megillah directly. With a microphone, or a hearing aid, the sound you hear is generated by vibrations within the instrument and thus you do not hear the original sound directly from its source and do not fulfill the Mitzvah.

ולכן תמה אני מאד על כמה מגדולי הרבנים שהתירו לשמוע מקרא מגילה דרך מגביר קול ואיך לא שמו לבם לדבר זה שרק קול תנודות של ממברנה שומעים ולא קול מקרא מגלה של אדם (מצטער אני שלפי זה נמצא שהאנשים אשר אזנם כבדה משמוע ומשתמשים במכשיר של מיקרופון וטלפון קטן לקרב את קול המדבר לאזנם שלפי"ז אינם יוצאים כלל חובת שופר ומקרא מגילה וכדומה) (שו"ת מנחת שלמה חלק א סימן ט).

Therefore, I am very surprised on many great Rabbis who permit listening to the reading of the Megillah through a microphone, and how do they not pay attention to this fact that you are only hearing the vibrations of a membrane and not the voice of the person reading the Megillah (And I am contrite that based on this those who are hard of hearing and use a hearing aid to bring the sound of a speaker to their ears, that based on this, they do not fulfill the obligation of Shofar or reading the Megillah and the like)  (Minchat Shlomo 1:9).

Thus, even though the hearing aid enables you to hear, since the sound is not the original sound, you cannot fulfill these Mitzvot.

On the other hand, Rav Ovadia Yosef believes that someone who hears via a prosthetic is indeed considered hearing, is fully obligated in these Mitzvot, and is therefore able to exempt others. His rationale is that hearing through an instrument is still considered hearing just like speaking through an intermediary, like dentures, is considered speaking.

למדנו ששמיעה ע"י כלי חשיבא שפיר שמיעה לדונו כפקח בכל דבריו. והוא הדין לדיבור ע"י כלי כגון שינים תותבות חשיב דיבור ממש לכל דבריו, ולהוציא את הרבים ידי חובתם, ואין שום ספק בדבר (שו"ת יביע אומר אורח חיים ז:יח).

We have learned that listening through an instrument is considered a hearing such that he is considered normal in all ways.  And the same thing for speaking through an instrument like dentures is considered actually speaking for all purposes, even to exempt others of their obligation and there is no doubt regarding the matter (Yabia Omer, Orach Chaim, 7:18).

Like we saw earlier, Rav Ovadia Yosef is concerned more with the ultimate experience of hearing, rather than the mechanism used to hear.

R' Tzvi Pseach Frank's position is that you can fulfill the Mitzvah of Megillah but not Shofar due to an additional requirement for the mitzvah of Shofar. The Mishna in Rosh Hashana explains that you only fulfill your obligation of hearing the Shofar if you hear the pure sound of the Shofar, not a הברה, an echo, of the sound.

התוקע לתוך הבור, או לתוך הדות, או לתוך הפיטס, אם קול שופר שמע - יצא, ואם קול הברה שמע - לא יצא. (תלמוד בבלי מסכת ראש השנה דף כז עמוד ב).

One who blows the Shofar into a pit, a cistern, or a tub, if he hears the sound of the Shofar, he has fulfilled his obligation, if he hears the sound of the echo, he has not fulfilled his obligation (Rosh HaShana 27b).

The Minchat Yitzchak quotes R' Tzvi Pesach Frank who suggests that what you hear through a hearing aid is a combination of the original sound with an additional sound generated by the hearing aid.

גם מה שכתב שם, דבמכונת שמיעה, אינו יוצא י"ח קריאת התורה ומגילה, לפום ריהטא לאו בחדא מחתא מחתינהו, דבמשנה ובגמרא מצינו לענין תקיעת שופר, דאם קול הברה שמע לא יצא, דבקול שופר מעכב אם יש בקול תערובת של שופר אחר או שאינו ממין שופר, אבל בקריאת התורה או מגילה, הרי שומע קול הקורא, אלא שמעורב גם קול אחר, יש לדון דשפיר יוצא גם כשנתערב בו מקול אחר, דהכל הוא מכח הקורא, וכל הקולות כשרים, אלא שיהי' מכח בר חיובא (שו"ת מנחת יצחק חלק ב סימן קיג).

That which is written there that with a hearing aid, you do not fulfill your obligation of listening to the reading of the Torah or the Megillah, they are not all made of one stamp. In the Mishna and Gemara we find that regarding blowing the Shofar, if you hear the sound of the echo you are not exempt since a valid sound of the Shofar is prevented if with this sound, there is the sound of another Shofar or something else mixed in.  But regarding reading the Megillah, he has heard the sound of the reader, just that there is another sound mixed in with it, then you have fulfilled your obligation even when there is another sound mixed in, since it is all from the power of the reader and all the sounds are valid provided that they come from the power of one who is obligated (Minchat Yitzchak 2:113).

Thus, since fulfilling the Mitzvah of hearing the Shofar requires hearing the unadulterated sound of the Shofar, you cannot fulfill this Mitzvah using hearing aids.  Listening to the Megillah, however, does not require hearing the pure sound of the Megillah, and thus you can fulfill it using hearing aids.

The Tzitz Eliezer agrees with R' Tzvi Pesach Frank's distinction between Shofar and Megillah although for slightly more nuanced reasons. The Tzitz Eliezer breaks down R' Tzvi Pesach Frank's rationale into two parts. According to R' Tzvi Pesach Frank, you fulfill your obligation for Megillah because 1 - you are hearing the original sound, albeit mixed in with an additional electronically generated sound, and 2 - both the original sound and the sound generated by the microphone (or hearing aid) are both generated by the voice of the person reading the Megillah.

ואם כי רישא דדבריו אינם תואמים לכאורה את המציאות, כי כאמור, כפי שאומרים המומחים לאותו דבר איננו כלל קול האורגנלי של האדם כי הקול חולף ונהפך לזרם וכו' ושוב מתחלפים הזרמים וחוזר ונוצר מחדש גלי קל /גלי קול/ וכו', אבל תפוס סיפא דדבריו, דיש לדון דשפיר יוצא בהיות דהכל מיהת הוא מכח הקורא וכל הקולות כשרים ובלבד שיהי' מוכח /מכוח/ בר חיובא (שו"ת ציץ אליעזר חלק ח סימן יא).

And even if the beginning of his [R' Tzvi Pesach Frank's] words do not reflect the reality, since according to the experts for that matter, it is no longer the sound of the original voice of the person reading at all since the voice changes to electricity and then the currents change and create a new sound, but we can use the end of his words, that you have fulfilled your obligation even when there is another sound mixed in, since it is all from the power of the reader and all the sounds are valid provided that they come from the power of one who is obligated (Tzitz Eliezer 8:11).

The Tzitz Eliezer believes that the first point is scientifically invalid. He explains that a sound from a microphone is not a combination of the original sound with a new sound, but solely an artificial sound which alone is not enough to fulfill the Mitzvah. However, regarding the second point, he explains that since this sound is caused by the person reading the Megillah, and since you hear it immediately after it was uttered by the person reading the Megillah, you can fulfill your obligation of hearing the Megillah even though the sound you hear is generated by the hearing aid. According to the Tzitz Eliezer, in order to fulfill this Mitzvah, you need to experience the sound immediately after it was generated, even if you don't hear the actual sound, but only an electronically generated imitation.

R' Moshe Feinstein seems to agree with this position of the Tzitz Eliezer. While discussing listening to the Megillah read through a microphone, he suggests that it is possible that you fulfill your obligation based on two reasons.  First of all, even though the sound we hear from the microphone is not the original voice, nonetheless, we can consider it the reader's actual voice since the sound is created by the voice of the reader. Additionally, he explains that any sound that we perceive has traveled through the air and is slightly delayed from the original source of the sound, and yet we consider that sound the original sound, so too a sound that we hear from the microphone, even though there is a slight delay as the sound feeds through the microphone and speaker system, nonetheless we may be able to consider it as the original sound.

וכן מסתבר לפי מה שאומרים חכמי הטבע שהקול יש לו הלוך עד האזן וגם יש קצת שיהוי זמן בהלוכו, ומ"מ נחשב שהוא קול האדם לכן אפשר שגם הקול שנעשה בהמיקראפאן בעת שמדבר ששומעין אותו הוא נחשב קולו ממש וכן הא יותר מסתבר (שו"ת אגרות משה אורח חיים חלק ב סימן קח).

And so it makes sense based on what the scientists say that sound has to travel to the ear and there is a delay in the time it takes to travel [from when it originated], but nonetheless we consider it the sound of the person, therefore it is possible that the sound that is generated through the microphone while the person is speaking that one who hears it is considered like he heard the actual sound, and this is reasonable (Igrot Moshe Orach Chaim, 2:108).

This opinion of R' Moshe Feinstein is interesting in light of his position mentioned earlier regarding the status of a deaf individual who can only hear with a hearing aid. R' Moshe Feinstein (Even HaEzer 3:33) believes that a hearing through a hearing aid does not transform a deaf person into a hearing person, since he is not hearing with natural, biological organs.  Yet here, R' Moshe believes that hearing an artificial sound through a microphone is considered hearing.  It is possible that the difference is that Rav Moshe believes that you need to have the natural ability to hear through your ears to be considered hearing. Once you have that ability, then if you hear the Megillah through a microphone for example, it may be valid, whereas if your only ability to hear is using an artificial device, then you would not be able to fulfill the Mitzvah because you have no natural capability of hearing. In other words, according to Rav Moshe there is a difference between changing the status of a deaf person and fulfilling a mitzvah.  In order to be considered a hearing person, an individual must achieve a certain standard of hearing using his natural organs.  Whereas to fulfill a particular Mitzvah, namely the Mitzvah of Megillah, a person must hear a viable sound and that sound can be created through the means of a microphone.

The crux of this discussion regarding hearing aids seems to be focused on whether or not the sound you hear with hearing aids is close enough to the original sound that you can fulfill the Mitzvah by hearing it. When it comes to cochlear implants, the story may be different. A cochlear implant uses a mechanism where no intermediate  sound is ever generated. By examining the developing discussion about cochlear implants more closely, what emerges is that the discussion about using prosthetics such as hearing aids may not simply be a discussion about the quality of the sound that enters your ear, but rather a broader discussion about whether artificial organs can have the same status as natural organs for the purposes of fulfilling a Mitzvah. Thus, if the issue is solely the fact that the sound you are hearing is not the original sound, then a cochlear implant should bypass the problem. If however, the problem is a broader one concerned with the natural ability to hear, then a cochlear implant may still be problematic.

One area of halacha that may reflect on this issue involves surgically implanted pacemakers. These pacemakers are expensive and durable and when a patient dies, the pacemaker can be removed from a corpse and re-implanted into another person.  From a halachic perspective there are two primary issues that must be dealt with in this kind of procedure: ניבול המת, desecrating the corpse, and הנאה מן המת, deriving benefit from a corpse. Both these actions are generally prohibited, but the discussion of benefiting from a corpse in this context may reveal whether surgically implanted devices can become integrated with the body such that it could be considered an organ of the body.

The initial prohibition to benefit from a corpse is learned from the Gemara in Avodah Zarah (29b) which compares an עגלה ערופה to a corpse; just as it is prohibited to benefit from an עגלה ערופה, so too it is forbidden to benefit from a corpse.  A second Gemara in Arachin (7a) explains that attachments to a corpse, such as a wig, are forbidden for benefit, unless the person stipulated that the wig be given to someone after they die.

Based on these passages there is a disagreement between the רמבם and the שלחן ערוך as to the status of hair and attachments to the body. The רמבם in הלכות אבל יד:כא explains that although a corpse is forbidden for benefit, its hair is permitted because it is not considered the body.

המת אסור בהניה כולו, חוץ משיערו--שהוא מותר בהניה, מפני שאינו גופו  הלכות אבל יד:כא)

Corpse is entirely forbidden to derive benefit from except for the hair - which is permitted to derive benefit from because it is not the body. (Laws of Mourning 14:21).

The טור and שלחן ערוך in יו"ד סימן שמט סעיף א however, disagree and explain that both the hair and adornments, like a wig, are forbidden for benefit like the corpse itself.

The פתחי תשובה, qualifies this and believes that not any object connected to the body is forbidden, but only adornments that function like a body part, such as a wig or a false tooth are forbidden.

Modern poskim invoke this discussion when discussing the status of a pacemaker vis a vis the body. One of the critical issues is whether a surgically implanted device is considered part of the body or merely an attachment that remains distinct from the body.  The מנחת יצחק writes in שו"ת מנחת יצחק חלק ז סימן קא that based on the שלחן ערוך, it is forbidden to remove the pacemaker.  He explains that something that is connected by virtue of being inserted and absorbed by the body is nullified to the body and forbidden for benefit, "היכא דמחובר בבלוע תוך גופו דבודאי בטל לגופו ואסור בהנאה" It is possible to explain that the מנחת יצחק believes that a surgically implanted mechanical device does not have its own status, but rather takes on the status of the body.

On the other hand, the Tzitz Eliezer relies on the the רמבם who believes that even if something is connected or interwoven with the body, its still not forbidden to derive benefit from the implanted device because it is not considered the body itself.

דיש לסמוך על כגון דא על דיעות המתירין דקא סברי שהמחוברים והקשורים לגוף המת לא נאסרים בהנאה, מפני דאינו גופו (שו"ת ציץ אליעזר חלק יד סימן פג

One can rely on those opinions that permit [removing the pacemaker] because they believe that something that is attached and tied up to the corpse is not forbidden for benefit, since it is not the body (Tzitz Eliezer 14:83).

Rav Shlomo Zalman Auerbach agrees with the Tzitz Eliezer and adds another reason why it is permitted to take out the pacemaker and explains that a pacemaker is different from other objects like wigs or false teeth that are adjoined to the body since the pacemaker requires external upkeep, such that it sometimes needs a battery replaced, which prevents it from being considered an actual part of the body (See נשמת אברהם יו"ד סימן שמט אות ג).

According to the מנחת יצחק if the pacemaker is indeed considered a part of the body since it is surgically implanted into the body, then perhaps a cochlear implant could also be considered part of the body like a regular ear regarding Mitzvot that require hearing.  This could be consistent with the פתחי תשובה's understanding of the halacha since the cochlear implant functions like a natural part of the body allowing the individual to hear.  According to the Tzitz Eliezer and Rav Shlomo Zalman Auerbach, however, even though the cochlear implant is surgically implanted, it may still be seen as an external, electronic device that remains distinct from the body even though it is attached.

In an article in Techumin (vol. 24), Dr. Yisrael Berma writes that a person who has a cochlear implant should be considered hearing for Mitzvot that require hearing including listening to Megillat Esther and hearing the Shofar, since all the reservations about using a hearing aid are based on the electronic medium generating a new sound, while a cochlear implant stimulates the auditory nerves without generating a sound. In line with this approach, it is reported in the name of Rabbi Moshe Tendler that anyone with a cochlear implant is considered hearing for all purposes and would permit him to blow the Shofar for others[1]. Dr. Yisrael Berma and Rabbi Moshe Tendler both seem to believe that the problem with hearing aids is a problem of not hearing the actual sound, a problem which is bypassed with the cochlear implant.

On the other hand, in a recent article in Tradition (Issue 42, vol 1), Rabbi J. D. Bleich, raises concerns as to whether the difference in mechanism between a hearing aid and cochlear implant is significant enough for the person wearing the cochlear implant to fulfill these Mitzvot. He explains that both hearing aids and cochlear implants use an intermediate mechanism to enable the person wearing them to hear. Hearing aids use artificial sounds while cochlear implants use electrical signals. In order to distinguish between these two devices one must assume that when it comes to Mitzvot that require hearing, the halacha prohibits using the artificial sound waves generated using electric signals in a hearing aid, but not electrically generated signals that directly stimulate the auditory nerves in a cochlear implant, a distinction which Rabbi Bleich seems to be unsure of. Rabbi Bleich's reservation highlights that the issue with cochlear implants and hearing aids may not be a local issue limited to the sound that one is hearing from a prosthesis but may reflect a broader problem of whether an artifical prosthesis can achieve the status of a natural limb in halacha.

As technology advances and people create devices and organs that help fill in gaps in the way we experience the world, there is a discussion as to the status of these different tools in halacha. One can follow the development of the status of individuals with the emergence of novel mechanisms and shed light on the nature of hearing and its relationship with identity in halacha. Additionally, as we make advances in medical technology and we begin to blur the line between synthetic and natural organs it is important to understand the place of artificial organs in halacha.