Sony Walkman NW-A35HN Instruction Manual page 6

Selecting fine audio equipment such as the unit you've just purchased is only the
start of your musical enjoyment. Now it's time to consider how you can maximize
the fun and excitement your equipment offers. This manufacturer, the Consumer
Electronics Association (CEA)® and the American Speech-Language-Hearing
Association (ASHA) want you to get the most out of your equipment by playing it
at a safe level; a level that lets the sound come through clearly without annoying
blaring or distortion and, most importantly, without damaging your sensitive
hearing.
Sound can be deceiving. Over time your hearing "comfort level" adapts to higher
volumes of sound. So what sounds "normal" can actually be loud and harmful to
your hearing. Guard against this by setting your equipment at a safe level BEFORE
your hearing adapts.