Volume Adjustment

The Talking Book device has two dedicated buttons for volume control: Volume Up, and Volume Down. As the names of the button indicates, Volume Up will increase audio volume by a pre-determined amount, and Volume Down will decrease audio volume by the same amount. These buttons are permanently dedicated to the volume function and not programmable by the content modules.

Functionally, there should be 10 to 15 gradations from Maximum Volume to Minimum Volume. Exactly how these steps are layed out, in terms of dB, will be left up to the audio or electrical engineering team who have more experience in audio engineering.

The device should remember the last volume level selected, so that on a subsequent use (through a power off-on cycle), the level is remembered and reused. If there is no previously set settings, such as out of the factory, the default level should be set the third or fourth least loud level of amplification, assuming that it will be a level where it's generally audible and not too loud as to be shocking to the user when turned on.

Audio Output Selection

Content modules being played are converted to analog audio, amplified according to the volume control setting, and outputted to one of two output:

  • If there is a set of headphones plugged into the 1/8" audio jack (the common size for portable audio headphones), audio is outputted to the headphones, bypassing the built-in speaker. All audio files, whether they are mono, or stereo, are played to both the Left and Right channels of the headphone.
  • If there isn't a headphone plugged in, the audio is played through the internal speaker. The Left/Right channels are mixed to play through the single speaker that is on the Talking Book.