Meeting Topic: Hearing Tests for iPhone / iPod Touch
Moderator Name: Jeff Bamford
Speaker Name: Carl Blackwood and Dr. Don Hayes, Unitron
Other business or activities at the meeting:
Next meeting: October 27, 2009: NY Convention Review.
7PM, RCC 361, Ryerson University
Meeting Location: RCC 361, Ryerson University, Toronto, ON
Dr. Don Hayes discussed the audiology of the uHear application as it relates to hearing. Hearing loss typically occurs as damage to the cochlea. Over time damage to the cochlea leads to permanent hearing loss. Dr. Hayes reviewed how the ear works. It is important to note that you hear with your brain, the ears are only the collectors of the sound waves.
Dr. Hayes reviewed the type of hearing loss, and noted that a 25 dB loss at any octave band is the definition of a hearing loss.
Most audiology devices present tones at predetermined octave bands at 25 dB HL. "HL" is hearing loss, audiologists create a standard curve that defines normal hearing. As "normal hearing" is different for each octave band, the "HL" designation allows normal hearing to be presented as a straight line, e.g showing no loss for each octave band.
Unitron wanted to allow an easy way to perform screenings, hence they took advantage of the computing power of the iPod. The software is presented to the user much like a hearing test, but Dr. Hayes stressed that it s a screening. This is because the calibration of the device isn't known or can't easily be determined, hence it should only be considered as a screeing. Their screening also includes "speech in noise", which becomes a problem for those over 35. A short questionnaire is also presented.
Carl Blackwood discussed the project from the perspective of the software. He noted that there are slight differences between the iPhone and iPod. For example, iPods do not have a built-in microphone. Meaning that it is not possible to determine the background noise level for example.
During their development, it was determined that it was easier to play a sound file as opposed to generating one in the device. The iPhone and iPod are relatively "flat" devices, but it was noted that new models appear to have a lower response and frequencies below those of interest for a hearing screening. Their development took into account that the sound files had to be an inverse of the hearing curve to ensure that they were "flat", to account for the coupling of the earbud into the ear and verification with other test methods.
The results were quite good, although the exact amount of hearing loss is not determined with their application , it is very useful as a screening device. The curves that generated by the device do match those that are made with audiometric devices.
