LoCHAid: An ultra-low-cost hearing aid for age-related hearing loss

Hearing aids are the primary tool in non-medical rehabilitation for individuals with hearing loss. While the costs of the electronic components have reduced substantially, the cost of a hearing aid has risen steadily to the point that it has become unaffordable for the majority of the population with Age-Related Hearing Loss (ARHL) especially for those residing in low- and middle-income countries. Here, we present an ultra-low-cost, affordable and accessible hearing aid device (‘LoCHAid’), specifically targeted towards treating ARHL in elderly patients. The LoCHAid components cost 98 cents (< $1) when purchased in bulk for 10,000 units and can be personalized for each user through a 3D-printable case. It is designed to be an over-the-counter (OTC) self-serviceable solution for elderly individuals with ARHL. Electroacoustic measurements show that the device meets most of the targets set out by the WHO Preferred Product Profile and Consumer Technology Association for hearing aids. The frequency response of the hearing aid shows selectable gain in the range of 4-8 kHz, and mild to moderate gain between 200-1000 Hz, and shows very limited total distortion (1%). Simulated gain measurements show that the LoCHAid is well fitted to a range of ARHL profiles for males and females between the ages of 60-79 years. Overall, the measurements show that the device offers the potential to benefit individuals with ARHL. Thus, our proposed design has the potential to address the challenge of affordable and accessible hearing technology for hearing impaired elderly individuals especially in low- and middle-income countries.

The LoCHAid components cost 98 cents (<$1) when purchased in bulk for 10,000 units and can be personalized for each user through a 3D-printable case.
The first sentence is rather odd and should be altered --do the authors mean that hearing aids are the primary tool in non-medical rehabilitation for persons with hearing loss? The "audiological market" as is written is a very vague and wide term and should be avoided.
-We have edited this to include that hearing aids are the primary tool in non-medical rehabilitation for persons with hearing loss. (Line 12-13)

Consumer Technology Association for Hearing Aids. I don't understand why Hearing
Aids is capitalized. We change the sentence to Second, we simulate the preferred gain for a range of ARHL profiles (SI Fig S1) in a coupler using the Audioscan Verifit device, and through a real ear simulator using the G.R.A.S KEMAR manikin. ( Line 69-71)

p. 4 better if "requires few soldering points"
-We have fixed it to "requires few soldering points" (Line 91-92). Thank you.
p. 5 line 143 The THD statement is misleading. WHO only allows 8% at certain low frequencies, not as an overall figure. This statement needs correction.
-We have fixed the sentence to -The total harmonic distortion at 500, 1000, and 1600 Hz is very low at 1%, much less than the limits posed by WHO (8% at 500 Hz & 800 Hz, 2% at 1500 Hz ), and CTA (5% at 500 Hz) (Line 143-145) p. 7 "strength 65 dB SPL" is rather unscientific. Better if "an ISTS signal of 65 dB SPL was played".
-We have fixed this to "an ISTS signal of 65 dB SPL was played." (Line 201) p. 9 To avoid over-generalization besterr to state "which often do not exist in LMIC".
-We have fixed this to include which often do not exist in LMIC (Line 241)

Line 259 Why the "($140)" in the text? Seems not reason for this to appear.
-We have removed the $140 from the text. (Line 259) p. 10 should be "mass manufacturer" [singular not plural].
-We have fixed this this to mass manufacturer. (Line 286) p. 11 line 317 better if "a lower EIN for the device".
-We have fixed this to "a lower EIN for the device" (Line 317) References : Not highlighted in text, as fixed in bibliography file.

Ref 3 should be "Beaver Dam"
Fixed.

Ref 4 should be Journal of Neuroscience -delete "
The" and "the official..." Fixed.

Ref 5 has no journal pages numbers
Fixed -added pg numbers 187-195.

Ref 15 National Academies of Sciences, Engineering, and Medicine should be capitalized.
Fixed.

Ref 37 No publication etc. details are provided.
Website -reference, url, access date is provided.

Ref 38 No publication etc. details are provided.
Website -reference, url, access date is provided We have furthermore added to figure captions in Figure 3 and Figure 4 the following sentence -The reader is referred to SI Figs S9-S79 and Tables I-LX for individual profile targets and responses. -We have added a space between the end of the sentence on Line 106 and the start of the next sentence -We have added space between the end of the sentence on Line 115 and the start of the next sentence.