microphone array project ece5525 – speech processing robert villmow 12/11/03
TRANSCRIPT
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Microphone Array Project
ECE5525 – Speech Processing
Robert Villmow12/11/03
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Microphone Array Purpose
Microphone Array Purpose• Improves sound reception when interfering
sources are located far enough apart • spatial separation
• Capable of determinig the direction a sound is coming from
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Background
Data sampled at each microphone is different due to different angles of arrival
Delay and Sum Algorithm• Assume a sound is arriving at a specific angle then calculate
when that sound will be sampled by the other microphones
• Sound arriving from desired angle will be correlated between microphones
• Sound arriving from other angles will be uncorrelated
• Summation of the data will attenuate uncorrelated signals
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15 Element Microphone Array
High
Middle
Low
Low Array• 4x spacing as high array
Middle Array• 2x spacing as high array
High Array• minimum spacing between microphones
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Microphone Sampling
Source at 10°
Source at 50°Source at 90°
Source at 0°
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Sampling Summary
Sample rate affects performance• sampled data differs between microphones
• algorithm depends on data being correlated between microphonesS
Sound sources at 0° are not affected by sample rate• sampled by all microphones at the same time
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High Array
Low Frequency Response• Similar to a single microphone
High Frequency Response• Narrow beam width
Frequency Responses at 4400 Hz
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Low Array
Low Frequency Response• Good Directional response
High Frequency Response• Too many Grating lobes
Frequency Responses at 800 Hz
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Block Diagram
BP FilterHigh Freq
BP FilterMiddle Freq
BPFilterLow Freq
2.5khz – 4.5khz
1.5khz – 2.5khz
300hz – 1.5khz
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Array Test Configuration
Speaker
Radio
45°
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CMU Microphone Array Data
15 Channels 16 kHz, 16-bit linear Sampling Files used
• an101-mtms-arr3A.adc• 3 cm spacing in a noisy computer lab
• Speaker is 1 meter from array
• an101-mtms-arr4A.adc• 4 cm spacing in a noisy computer lab
• Speaker is 1 meter from array
• an101-mtms-arrCR1A.adc• 4 cm spacing with radio at 45°
• Speaker at a distance of 1 meters
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-100 -80 -60 -40 -20 0 20 40 60 80 1002.5
3
3.5
4x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1000.5
1
1.5
2
2.5
3
3.5x 10
7 Mean Squared Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1002.5
3
3.5
4x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1001
1.5
2
2.5
3
3.5x 10
7 Mean Squared Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1002
3
4
5
6x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1000.5
1
1.5
2
2.5
3
3.5x 10
7 Mean Squared Error - Summed vs. Single Channel
Arr3A Results
Difference – Single Channel vs. Summed signal
Mean Squared Error – Single Channel vs. Summed signal
High Middle Low
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Arr3A – Mean Squared Error
Array Max Min
High 9.8070 x 106 3.3647 x 107
Middle 1.0517 x 107 3.4093 x 107
Low 7.7878 x 106 3.1970 x 107
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-100 -80 -60 -40 -20 0 20 40 60 80 1002
2.5
3
3.5
4x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8x 10
7 Mean Squared Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1001.5
2
2.5
3
3.5
4x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8x 10
7 Mean Squared Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1002
2.5
3
3.5
4x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8x 10
7 Mean Squared Error - Summed vs. Single Channel
Arr4A Results
Mean Squared Error – Single Channel vs. Summed signal
Difference – Single Channel vs. Summed signal
High Middle Low
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Arr4A – Mean Squared Error
Array Max Min
High 8.1192 x 106 6.7789 x 107
Middle 8.3030 x 106 6.8715 x 107
Low 6.3974 x 106 6.7689 x 107
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-100 -80 -60 -40 -20 0 20 40 60 80 1002.5
3
3.5
4
4.5x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1004
6
8
10
12
14x 10
6 Mean Squared Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1002
2.5
3
3.5
4
4.5x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1004
6
8
10
12
14x 10
6 Mean Squared Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1002.5
3
3.5
4x 10
4 Maximum Peak Error - Summed vs. Single Channel
-100 -80 -60 -40 -20 0 20 40 60 80 1004
6
8
10
12
14x 10
6 Mean Squared Error - Summed vs. Single Channel
ArrCR1A Results (Interpolated)
Difference – Single Channel vs. Summed signal
Mean Squared Error – Single Channel vs. Summed signal
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ArrCR1A – Mean Squared Error
Array Max Min
High 5.0761 x 106 1.2176 x 107
Middle 5.2716 x 106 1.3283 x 107
Low 4.3089 x 106 1.3238 x 107
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Sound Results
Sound Files...
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Summary
Microphone array increases SNR Array Response is best at angles between
±30° Oversampling smoothes array response
• increased computations
• decreases performance lost due to sampling