(a) Execute the calculation of the anti-aliasing filter sampling frequency and its bandwidth. Hence, plot the ideal bandwidth spectrum of the filter.

(b) Analyse the ADC quantization level that is required to cover the full voltage swing of 5 V peak-to-peak of the audio input signal. Hence, obtain its quantization error range with the rounding rule being used in the ADC conversion.

(c) Analyse the ADC binary representation for an instantaneous audio input signal of -2.2 V.

(d) Describe the audio performance through the calculation of the total harmonic distortion (THD) at the output of the amplifier in percentage. Hence, plot the amplitude spectrum of the output of the amplifier.
(a) Given that a Macbook Pro laptop is receiving a music stream and passes this music to an audio multiplicative mixer Apple software is inside the system. This music has three signal components with frequency at the Middle C note and its third and fifth harmonics with amplitude of 3 volts, 2 volts, and 1 volt peaks respectively.

(i) Obtain the Middle C Note frequency and its respective harmonic of the music stream where 𝑝 = 60. Hence, describe the frequency spectrum for the music stream. Hint: 𝑝 = 69 + 12 𝑙𝑜𝑔2 ( 𝑓 440) 𝐻𝑧

(ii) The music stream passes through the multiplicative mixer Apple software. It produces various beat frequencies among each other. Explain the mixing
process by calculating the mixed and beat frequencies.

(iii) Analyse through plotting the amplitude spectrum of the output of the
multiplicative mixer in Question 2(a)(ii). Clearly indicate the beat frequencies
in the plot.

(b) Given that amplitude modulation (AM) technology is being used to broadcast the audio music stream via Wi-Fi technology. The audio modulating signal is given as 𝑏(𝑡) = 1 + 8 cos(2𝜋𝑓𝑡) V where 𝑓 is the frequency of the fifth harmonic in the music stream in

Question 2

a (i). The carrier is given as 𝑝(𝑡) = 5 cos(10000000000𝜋𝑡) V.
(i) Derive and analyze through plotting the frequency spectrum of the modulated signal.

(ii) Determine the receiver carrier frequency used and determine the bandwidth of the recovering filter to recover the modulating signal.

Question 3

(a) Discuss withdrawing how the mechanism of the human ear protects the ear from loud sound.

(b) The DVD sampling rate is 176.4 kHz, and 20-bit coding is employed to record 500 minutes of a two-channel stereo uncompressed musical song where each song is 5 minutes in duration with an interval of 10 seconds separation. Execute the calculation to analyze the number of DVDs required to store the songs, assuming a DVD size is 4.7 GB.

(c) MIDI protocol is used to demonstrate the application of audio technology in
multimedia. A set of MIDI subroutines is attached below. They can be used in a
C-language program to control MIDI device. The subroutine parameters can be specified in the MIDI specification in Appendix I and all parameter values must be in hexadecimal format. Please use the subroutines to do the following operations

(i) System Active Sensing

(ii) System Start and select song number 20 at the starting point at a count of 500
(iii) Channel 12 plays Middle C note for 5000 ms at middle volume and then
maximum volume.
(iv) Channel 15 plays note at 880 Hz for 7000 ms at middle volume and then quarter volume by following the formula to obtain pitch value which is given as P = 69 + 12log2(f/440).

(v) Channel 14 plays note at 440 Hz for 8200 ms at middle loudness and then total silent by following the formula to obtain pitch value which is given as P = 69 + 12log2(f/440).

Question 4

(a) Analyse the power difference (PD) reduction in dB at the receiver for two audio signals that have traveled 20 m and 30 m respectively. Assume uniform media transmission. Explain the power at the receiver when both direct and reflected audio signals are totally in phase with each other and equal in strength. Suggest one applicationB that makes use of this phenomenon.

(b) Assuming an audio sound source is transmitting an audio signal at 30 degrees at the right with respect to the center of a human, obtain its Inter-aural delay (ITD) of audio sound. Assuming the distance between two ears is 35 cm. Hence, analyze the perception capability of the human ear with the calculated ITD. Assume the speed of sound wave in air is 330 m/s.