Question 4

Analyse the power difference (PD) reduction in dB at the receiver for two audio signals

that have travelled 20 m and 30 m respectively. Assume uniform media transmission.

Explain the power at the receiver when both direct and reflected audio signal are totally

in phase with each other and equal in strength. Suggest one application that make use

of this phenomena.

(b)

SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS)

MTD205

(3 marks)

(c)

(9 marks)

Assuming an audio sound source is transmitting audio signal at 30 degrees at the right

with respect to the centre of a human, obtain its Inter-aural delay (ITD) of audio sound.

Assuming the distance between two ears is 35 cm. Hence, analyse the perception

capability of the human ear with the calculated ITD. Assume the speed of sound wave

in air is 330 m/s.

(7 marks)

Page 45

Tutor-Marked Assignment

To create sound echoes, reverberation filter is used to produce various reflection sound.

Its output response is given as y(n) = x(n − 1) − g * y(n − 3) where x(n) is the

input power level sequence of (10, 11, 9, 7, -1, -2,-8...0) and g is the coefficient that

determines the decay level of reverberation with a value of 2. Draw the Infinite Impulse

Response (IIR) filter implementation of the above filter and determine the output at 8

seconds. Assume input and output remains 0 when n = 0 and n is an integer.

(9 marks)