export_27 acoustics

Question 1

%ALCONS

Answer 1

percent articulation loss of consonants in speech. This number gives us an estimate as to the percentage of loss in intelligibility. In most cases, a 8 - 10%ALCONS is considered acceptable.

Question 2

STI

Answer 2

speech transmission index. This number looks at the issue from the reverse position in that it is giving us the amount of data that is making through to the intended listener. Here, an STI of 0.75 - 1.0 is considered excellent.

Question 3

TEF

Answer 3

(Time Energy Frequency) electronic instrumentation can test for STI and %ALCONS.

Question 4

Production of sound

Answer 4

how the energy is generated, i.e. the source of the

sound

Question 5

Propagation of sound

Answer 5

the pathway of the energy

Question 6

Interaction of sound

Answer 6

how material responds to the sound energy imposed

upon it

Question 7

Reception of sound

Answer 7

how hearers’ ears and brains will respond to the stimuli

placed upon them

Question 8

Law of Conservation of Energy

Answer 8

The Law of Conservation of Energy says that the total energy cannot be created nor destroyed. Energy can be transformed from one form to another, and transferred from one body to another. but the total amount of energy remains constant.

Question 9

precedence or Haas effect

Answer 9

If aaudio reflection arrives within a certain time period after the direct sound, our ear/brain system integrates the two arrivals into one.

Question 10

Flutter Echoes

Answer 10

A flutter echo is a series of

reflections that continue to bounce back and forth between parallel hard surfaces, such as large walls or windows.

Question 11

Reverberation

Answer 11

Reverberation is the combination of many acoustic
reflections that are dense enough in time so as to not be
audible as reflections but instead to act as a statistical
sonic decay “ tail” to sounds in the room .

Question 12

Reverberant Field

Answer 12

A statistical reverberant field is reverberation that is well enough spatially diffused that it is essentiaHy the same at all points in a room . Many of the formulas we use in acoustics and sound systems assume the existence of a statistical reverberant field , but this does not always exist. When we talk about the reverberation time (RT60) of a room we are assuming the room has a statistical
reverberant field .

Question 13

Reverberation Time

Answer 13

Persistence of sound energy (reverberation) is measured in time and level.
It is also frequency specific. The reverberation time of a space is said to be
the number of seconds it takes for the sound to decay to one thousandth of
its original level, or 60 dB. Therefore, we call this the RT 60 for a room.

Question 14

sound

absorption coefficient

Answer 14

The degree to which a material is absorptive

Question 15

Noise Reduction Coefficient

Answer 15

The NRC (Noise Reduction Coefficient) takes an average of the four middle test frequencies (250, 500, 1000 and 2000)

Question 16

Sabin

Answer 16

Sabin is a non-metric unit of sound absorption used in
acoustical engineering . One sabin is the sound
absorption of one square foot of a perfectly absorbing
surface, such as an open window . The sound
absorption of one square meter of a perfectly
absorbing surface Is a metric sabin.

Question 17

STC

Answer 17

Sound Transmission Class rates transmission loss at speech frequencies from 125 - 4000 Hz
plotted against a standard contour as the reference. STC does not evaluate
performance at frequencies below 125 Hz where music and mechanical
equipment noise levels can be high.

Question 18

llC (Impact Insulation Class)

Answer 18

Impact insulation class (llC) is a rating used to quantify impact sound absorption . It is an average of the attenuation in decibels that occurs at frequencies ranging from 100 to 3150 Hz . The higher the llC rating is, the better insulation from impact noise the material provides .