Amazon.com, Inc.
Acoustic unit for wearable device

Abstract:

A hybrid acoustic unit operates as an acoustic monopole for frequencies of audio output below a threshold frequency and as an acoustic quadrupole for frequencies above the threshold frequency. A first transducer provides the low frequencies below the threshold frequency while a second transducer provides the high frequencies above the threshold frequency. The low frequencies improve perceived loudness to a user while being masked from bystanders due to ambient noise. A region of an acoustic pattern produced by the acoustic quadrupole is directed towards an ear of the user. This improves audibility to the user while substantially reducing loudness of those high frequencies to bystanders.