Tutor-Marked Assignment – Global Homework Experts

MTD205
Audio Technology
Tutor-Marked Assignment
July 2022 Presentation

MTD205 Tutor-Marked Assignment
SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS) Page 2 of 7
TUTOR-MARKED ASSIGNMENT (TMA)
This assignment is worth 15% of the final mark for MTD205 – Audio Technology.
The cut-off date for this assignment is
30 August 2022, 23:55 hrs.
Note to Students:
You are to include the following particulars in your submission: Course Code, Title of the
TMA, SUSS PI No., Your Name, and Submission Date.
Submit your typed solution document in the form of a single MS Word file (saved as
MTD205_TMA01_yourname.docx) on or before the cut-off date shown above. Ensure Turnitin
plagiarism score is minimum.
Question 1
An audio earpiece such as Apple Airpods Pro has spatial audio feature that can track human
head movement to give surround sound effect. Assuming you are listening to the audio that is
streaming from the Macbook Pro to your earpiece, the audio signal has a fundamental
component of 4 KHz and its second harmonics at 0.25 V and 0.125 V respectively. It passes
through the anti-aliasing filter before it goes through the 8 bits 2’s complement ADC inside the
earpiece to process the audio signal fidelity. The processed audio signal goes through an
amplifier with a volume gain of 3 and produces additional 4
th and 5th harmonics at 0.075 V and
0.05 V respectively.

order now
(a) Execute the calculation of both sampling frequency and bandwidth of the anti-aliasing
filter. Hence, plot the 3 dB bandwidth spectrum.

(5 marks)
(b) Analyse the quantization level that is required to cover the full voltage swing of 2 V
peak-to-peak of the spatial audio input signal at the earpiece. Hence, obtain the
quantization error range with the truncation rule being used in the conversion process
of ADC.
(6 marks)
(c) Analyse the ADC binary representation for an instantaneous audio input signal of
-0.6 V.
(8 marks)
(d) Describe the quality of the earpiece audio performance by calculating its total harmonic
distortion (THD) at the amplifier output in percentage. Hence, plot the amplitude
spectrum of the amplifier at the output.
(6 marks)

MTD205 Tutor-Marked Assignment
SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS) Page 3 of 7
Question 2

(a) A YouTube music is streaming online from the Internet to a computer that is equipped
with an audio multiplicative mixer software. The music has three signal components

with frequency of 4 kHz, 9 kHz, and 19 kHz with amplitude of 4 V, 2 V and 1 V peaks
respectively.
(i) Describe the frequency spectrum for the music.
(2 marks)

(ii) The music passes through the computer’s multiplicative mixer software. It
produces various beat frequencies among each other. Explain the mixing

process by calculating the beat frequencies.
(9 marks)
(iii) Analyse through illustration on the amplitude spectrum of the output of the
multiplicative mixer in Question 2(a)(ii). Hence, indicate the beat frequencies
in the plot.
(4 marks)
(b) An amplitude modulation (AM) technology is used where the audio music signal is
broadcasting to the ship for crew entertainment via skywave propagation. The audio
modulating signal is given as
𝑏(𝑡) = 1 + 8 cos(20000𝜋𝑡) V while the carrier is given
as
𝑝(𝑡) = 5 cos(20000000𝜋𝑡) + 5 cos(30000000𝜋𝑡) V.

(i) Derive and analyse through illustration on the frequency spectrum of the spatial
modulated signal.

(7 marks)

(ii) Determine the receiver carrier and derive the bandwidth of the recovering filter
in order to recover the modulating signal.

(3 marks)
Question 3

(a) Discuss with illustration on the principle of critical band and frequency masking.
(5 marks)

 

(b) The Blue-ray sampling rate is 192 kHz and 24 bits coding are employed to record 1000
minutes of two channel stereo uncompressed song. Execute the calculation to analyse

the number of Blue-ray required to store the songs, assuming a DVD size is 25 GB.
(5 marks)
(c) MIDI protocol is used to demonstrate the application of audio technology in
multimedia. A set of MIDI subroutines is being 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.
MTD205 Tutor-Marked Assignment
SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS) Page 4 of 7
(i) System Reset
(3 marks)
(ii) System Start and select song number 11 at starting point at a count of 200
(3 marks)
(iii) Channel 10 plays low piano A note for 2000 ms at maximum volume and then
middle volume.
(3 marks)
(iv) Channel 12 plays note at 7040 Hz for 1000 ms at quarter volume and then middle
volume following formula to obtain pitch value given as P = 69 + 12log
2(f/440).
(3 marks)
(v) Channel 15 plays note at 3520 Hz for 3000 ms at middle loudness and then silent
following formula to obtain pitch value given as P = 69 + 12log
2(f/440).
(3 marks)
Question 4

(a) Discuss and illustrate early reflection and late reverberation. Hence explain the critical
distance.

(5 marks)
(b) Analyse the power difference (PD) reduction in dB at the receiver for two sound signals
that have travelled 5 m and 25 m respectively. Assume uniform media transmission.
Explain what is the consequence when both direct blocked and reflected sound signal
are totally out of phase with each other but equal in strength. Name
ONE (1) application
that use this feature.
(8 marks)
(c) Assume a human wear a spatial audio tracking earpiece that tracks the head movement
with respect to the sound source. The sound source is transmitting music signal at 50
degrees at the right with respect to the centre of the human. Obtain the Inter-aural delay
(ITD) of sound waves, assuming the distance between two ears is 30 cm. Analyse the
differentiating capability of the ear with the calculated ITD. Assume the speed of sound
wave in air is 340 m/s.
(5 marks)
(d) 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 – 2) where 𝑥(𝑛) is the
input power level sequence of {12, 12, 9, 8, -2, -1, -1, -6…0} and
𝑔 is the coefficient
that determines the decay level of reverberation with a value of 0.2. Draw the Infinite
Impulse Response (IIR) filter implementation of the above filter and determine the
output at 9 seconds. Assume input and output remains 0 when
𝑛 = 0 and n is an integer.
(7 marks)

MTD205 Tutor-Marked Assignment
SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS) Page 5 of 7
Appendix I

Binary Hex Message Type Channel Data Required
Data Byte 1 Date Byte 2
1000 8 Note off 1-16 Pitch (0-127) Velocity (0-127)
1001 9 Note on 1-16 Pitch (0-127) Release Velocity (0-127)
1010 A Polyphonic
aftertouch
1-16 Pitch (0-127) Aftertouch value
1011 B Control change 1-16 Controller type (0-127) Value (0-127)
1100 C Program change 1-16 Program-change value
(0 – 127)
1101 D Aftertouch 1-16 Aftertouch Value (0-
128)
1110 E Pitch bend 1-16 Bend value (0 – 127), often (0 -16383)
1111 F System 1-16 Variable number of bytes

Table Q3-1 MIDI Message Types
Table Q3-2 MIDI Control Change Messages

MTD205 Tutor-Marked Assignment
SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS) Page 6 of 7

Status Byte Followed by
Binary Hex Message Type Data Bytes
1111 0000 F0 System exclusive Various number
1111 0001 F1 Quarter frame message 1
1111 0010 F2 Song position pointer 2
1111 0011 F3 Song select 1
1111 0110 F6 Tuning request 0
1111 0111 F7 End-Of-Exchange (EOX) 0
1111 1000 F8 MIDI clock 0
1111 1010 FA Start 0
1111 1011 FB Continue 0
1111 1100 FC Stop 0
1111 1110 FE Active sensing 0
1111 1111 FF System reset 0

Table Q3-4 MIDI Note values in decimal

86 D”
84 C”
83 B’
81 A’
79 G’
77 F’
76 E’
74 D’
72 C’
71 B
70 –
69 A
68 –
67 G
66 –
65 F
64 E
63 –
62 D
59 B,
57 A,
55 G,
53 F,
52 E,
50 D,
48 C,
MIDI
Note Pitch
Pitch
MIDI
Note
MIDI
Note Pitch

61 –
60 C
Table Q3-3 MIDI Control Messages
MTD205 Tutor-Marked Assignment
SINGAPORE UNIVERSITY OF SOCIAL SCIENCES (SUSS) Page 7 of 7
Table Q3-5 : MIDI NOTE NUMBER TO EQUAL TEMPERAMENT SEMITONE TO
HERTZ CONVERSION TABLE
o Middle C = MIDI Note #60 • Low Piano A = MIDI Note #21 • MIDI Note # range 0-127
o Approximate ideal human hearing range 20-20,000 Hz
o Ratio Between Consecutive Semitones = 1:12th Root of 2 or 1:1.05946

12 C 16.4
13 C# 17.3
14 D 18.4
15 D# 19.4
16 E 20.6
17 F 21.8
18 F# 23.1
19 G 24.5
20 G# 26.0
21 A 27.5
22 A# 29.1
23 B 30.9
36 C 65.4
37 C# 69.3
38 D 73.4
39 D# 77.8
40 E 82.4
41 F 87.3
42 F# 92.5
43 G 98.0
44 G# 103.8
45 A 110.0
46 A# 116.5
47 B 123.5
60 C 261.6
61 C# 277.2
62 D 293.7
63 D# 311.1
64 E 329.6
65 F 349.2
66 F# 370.0
67 G 392.0
68 G# 415.3
69 A 440.0
70 A# 466.2
71 B 493.9
84 C 1046.5
85 C# 1108.7
86 D 1174.7
87 D# 1244.5
88 E 1318.5
89 F 1396.9
90 F# 1480.0
91 G 1568.0
92 G# 1661.2
93 A 1760.0
94 A# 1864.7
95 B 1975.5
108 C 4186.0
109 C# 4434.9
110 D 4698.6
111 D# 4978.0
112 E 5274.0
113 F 5587.7
114 F# 5919.9
115 G 6271.9
116 G# 6644.9
117 A 7040.0
118 A# 7458.6
119 B 7902.1
na C 16744.0
na C# 17739.7
na D 18794.5
na D# 19912.1
na E 21096.2
na F 22350.6
na F# 23679.6
na G 25087.7
na G# 26579.5
na A 28160.0
na A# 29834.5
na B 31608.5
24 C 32.7
25 C# 34.6
26 D 36.7
27 D# 38.9
28 E 41.2
29 F 43.7
30 F# 46.2
31 G 49.0
32 G# 51.9
33 A 55.0
34 A# 58.3
35 B 61.7
48 C 130.8
49 C# 138.6
50 D 146.8
51 D# 155.6
52 E 164.8
53 F 174.6
54 F# 185.0
55 G 196.0
56 G# 207.7
57 A 220.0
58 A# 233.1
59 B 246.9
72 C 523.3
73 C# 554.4
74 D 587.3
75 D# 622.3
76 E 659.3
77 F 698.5
78 F# 740.0
79 G 784.0
80 G# 830.6
81 A 880.0
82 A# 932.3
83 B 987.8
96 C 2093.0
97 C# 2217.5
98 D 2349.3
99 D# 2489.0
100 E 2637.0
101 F 2793.8
102 F# 2960.0
103 G 3136.0
104 G# 3322.4
105 A 3520.0
106 A# 3729.3
107 B 3951.1
120 C 8372.0
121 C# 8869.8
122 D 9397.3
123 D# 9956.1
134 E 10548.1
125 F 11175.3
126 F# 11839.8
127 G 12543.9
na G# 13289.8
na A 14080.0
na A# 14917.2
na B 15804.3
na C 33488.1
na C# 35479.4
na D 37589.1
na D# 39824.3
na E 42192.3
na F 44701.2
na F# 47359.3
na G 50175.4
na G# 53159.0
na A 56320.0
na A# 59669.0
na B 63217.1

—- END OF ASSIGNMENT —-