What is the absolute power of a sound with an intensity of X dB IL? What is the absolute power corresponding to 20 dB IL? What is the absolute power corresponding.

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Presentation transcript:

What is the absolute power of a sound with an intensity of X dB IL? What is the absolute power corresponding to 20 dB IL? What is the absolute power corresponding to 20 dB IL? Answer: w/m 2 Answer: w/m 2 What is the absolute power corresponding to 80 dB IL? What is the absolute power corresponding to 80 dB IL? Answer: w/m 2

What is the absolute pressure of a sound with an intensity of X dB SPL? What is the absolute pressure corresponding to 60 dB SPL? What is the absolute pressure corresponding to 60 dB SPL? Answer: 2 x 10 4 or 20 x 10 3 μPa Answer: 2 x 10 4 or 20 x 10 3 μPa What is the absolute pressure corresponding to 140 dB SPL? What is the absolute pressure corresponding to 140 dB SPL? Answer: 2 x 10 8 or 20 x 10 7 μPa Answer: 2 x 10 8 or 20 x 10 7 μPa

Sound fields Sound field: Any environment that contains sound Sound field: Any environment that contains sound Free field: Sound field without any reflections Free field: Sound field without any reflections Anechoic room: Artificial free field with no echoes Anechoic room: Artificial free field with no echoes Reverberant/echoic field: Sound field with reflections Reverberant/echoic field: Sound field with reflections Diffuse fields: Type of reverberant field with uniform sound intensity throughout the field. Diffuse fields: Type of reverberant field with uniform sound intensity throughout the field.

Sound propagation with distance in a free field I  1/(r 2), I  1/(r 2), where I is the intensity of the sound, P is the power of the sound at the source, and r is the distance from the source to the point of measurement.

Sound pressure and distance Sound pressure and distance p  1/r where p = sound pressure, r = distance from source where p = sound pressure, r = distance from source

Sound propagation with distance in a field with obstacles Impedance: Opposition to vibration Impedance: Opposition to vibration Two forms: Two forms: Reactance (X) Reactance (X) Resistance (R) Resistance (R) Remains same across frequencies Remains same across frequencies