Part 1 – Acoustic Fundamentals
• Expressing sound in decibels
• Summing SPL
• Inverse square law
• System level
, Decibels are a scale for measuring a change in
power.
æ W1 ö
10 log ç ÷
è W0 ø
So an increase from 1W to 100W is:
æ 100 ö
10 log ç ÷ = +20dB
è 1 ø
If we double the power (a ratio of 2/1), we get an
increase of 3dB:
10 log ( 2) = +3dB
, Every factor of 10 is equal to an increase of 10 dB
Power Level (re: 1 watt)
1000 w 30 dB
100 w 20 dB
10 w 10 dB
1w 0 dB
0,1 w -10 dB
0,01 w -20 dB
0,001 w -30 dB
• Expressing sound in decibels
• Summing SPL
• Inverse square law
• System level
, Decibels are a scale for measuring a change in
power.
æ W1 ö
10 log ç ÷
è W0 ø
So an increase from 1W to 100W is:
æ 100 ö
10 log ç ÷ = +20dB
è 1 ø
If we double the power (a ratio of 2/1), we get an
increase of 3dB:
10 log ( 2) = +3dB
, Every factor of 10 is equal to an increase of 10 dB
Power Level (re: 1 watt)
1000 w 30 dB
100 w 20 dB
10 w 10 dB
1w 0 dB
0,1 w -10 dB
0,01 w -20 dB
0,001 w -30 dB
