According to the device’s published specs, SpeechEasy hearing aid-style DAF devices have 15 dB default amplication with a maximum volume of 105 dB.[ref]ANDREW STUART, SHIXIONG XIA, YINING JIANG, TAO JIANG, JOSEPH KALINOWSKI, MICHAEL P. RASTATTER. 2003. Self-Contained In-the-Ear Device to Deliver Altered Auditory Feedback: Applications for Stuttering. Annals of Biomedical Engineering, Vol. 31, p. 235, 2003.[/ref] This volume can cause permanent hearing damage in five minutes.[ref]Acoustical Solutions, “Noise Level Data Tables,” http://www.acousticalsolutions.com/education/pdfs/Noise_Level.pdf; and “Noise and Hearing Loss,” http://www.asha.org/public/hearing/disorders/noise.htm[/ref] Because the devices pick up background noise, 90 dB of background noise could be amplified to 105 dB. This suggests that wearing a SpeechEasy device while walking near heavy traffic, or in a gymnasium, during applause in an auditorium, or at a distance from a jackhammer or subway train could permanently damage hearing.
On the SpeechEasy website discussion forum, users reported pain, ringing in their ears, and inabiliity to hear in the presence of background noise:
Sirens and the screeching brakes of train produce a piercing ringing in the ear that causes headaches. [ref]Williams, John. “Discovering the Power of Fluency,” National Organization on Disability, October 11, 2005, http://www.nod.org/index.cfm?fuseaction=page.viewPage&pageID=1430&nodeID=1&FeatureID=1546&redirected=1&CFID=7704440&CFTOKEN=76087310. See also sgfriend, The SpeechEasy Discussion Board, Jun 22, 2004, http://www.speecheasy.com/phpBB2/viewtopic.php?t=296[/ref]
I would also like it if they would make it so that when I leave the gym I don’t have to worry about ringing in my ears from it being so loud.[ref]axewarrior20, The SpeechEasy Discussion Board, Aug 07, 2003, http://www.speecheasy.com/phpBB2/viewtopic.php?t=121[/ref]
I asked Cory Portnuff, Au.D., Ph.D., to evaluate a SpeechEasy device. Dr. Portnuff did his dissertation on hearing damage from iPods.
The results were that 90 dB background noise resulted in 96.7 dBA output in the ear. This volume can be tolerated for up to 30 minutes without risk of hearing damage. The test used multitalker babble noise, which sounds similar to a restaurant or party.
Dr. Portnuff didn’t test louder volumes because above 90 dB background noise it’s difficult to have a conversation.
He also found that he was unable to hear the SpeechEasy’s DAF signal in his own ear when background noise exceeded 80 dBA.
In conclusion, a SpeechEasy device should be safe if you remove it or turn it off if
- You can no longer hear the DAF signal.
- When background noise exceeds 90 dB. (There are iPhone apps to measure background noise, such as “SPL Meter.”)
- You experience ringing in your ear or pain from loud noises.
Conversely, if you wear a SpeechEasy sixteen hours a day, without ever adjusting the volume, and “grit your teeth” through pain from loud noises, you could damage your hearing.