Method and apparatus for objective assessment of in-ear device acoustical performance

A method for assessing in-situ an acoustic seal of an in-ear device using an apparatus having a first sound measurement device and a second sound measurement device connected thereto, the in-ear device having a passageway extending therethrough, the passageway being in fluid communication with an ear canal of an ear when the in-ear device is inserted therein, the first and second sound measurement devices being removably engageable into the passageway, said method comprising:

• a) calibrating at least one of said first or second sound measurement devices by measuring a reference sound level with said sound measurement device when being submitted to a reference sound source and when being located in a close relationship relative thereto;
• b) measuring a first sound level outside the ear canal with the first sound measurement device when submitted to the sound source and when located in a close relationship relative to the in-ear device and outside the ear canal;
• c) simultaneously measuring a second sound level inside the ear canal with the second sound measurement device when submitted to the sound source and when engaged into and occluding the passageway with the in-ear device inserted inside the ear canal;
• d) assessing the acoustic seal of the in-ear device by subtracting said second sound level from said first sound level;
• and
• e) assessing validity of said first and second sound levels by determining coherence between said first and second sound levels, if not steps b) and c) are repeated.