19/02/07 12:45:54.02 AoUjzP1i.net
海外の自転車専門誌が行ったイヤホンとカーステ使用時の周囲音の聴こえやすさ比較実験
URLリンク(rideonmagazine.com.au)
Using our own taste as a guide, we established that a reasonable volume for l
istening to music through our earphones while riding at our location was three
clicks down from the maximum volume of our iPod, which turned out to be 87dB;
greater than the average peak of the ambient noise.
We then set up with testers 10 metres apart. One called out “Passing”, then
rang a bike bell, and neither registered on the decibel meter above the ambient
noise. Despite this, when a tester put the ear-bud earphones in and played
music at 87dB, they could clearly hear their fellow tester’s call out, and the
ringing of the bike bell.
The call and bell could also be heard with the in-ear earphones, but only faintly.
What was startling, however, was what could be heard from the car with its
stereo on at what was perceived as a moderate level; (69dB). Our driver was
unable to hear our tester, stationed 10 metres away, calling out “Passing”,
or the bike bell. Without the car stereo on it was just possible to hear the
call and bell; it registered at a similar level to having the in-ear headphones in.
Conclusions
Based on these relatively simple tests, it is fair to conclude that:
A bike rider with ear-bud earphones playing music at a reasonable volume
hears much more outside noise than a car driver, even when that driver
has no music playing.
A bike rider with in-ear earphones playing music at a reasonable volume
hears about the same outside noise as a car driver with no music playing,
but more than a car driver playing music.
Ear-bud earphones set at a reasonable volume still allow riders to clearly
hear the warning sounds of other riders.