¾ NAM Microphone = Sensor for Sampling Flesh ConductedSoft Breathed Voices (Non(Non-Audible Murmur; NAM)
NAM)
¾ BTOS (Body Transmitted Ordinary Speech) = Flesh

Conducted Normal Speech sampled by NAM Microphone

Evaluation of Soft Silicone
Type NAM Microphones

Stethoscopic NAM Microphone

Applied Linguistic Lab.
YOSHITAKA NAKAJIMA
25 Feb. 2005
1

Soft Silicone NAM Microphone

2NAM

OCMSS

OECM

OCWSS
OCMSS Type

OECM

TMSS

OCWSS TypeTMSS Type

3BTOS
OCMSS

4

Synchronous Stereo Sampling of Air and Flesh
Conducted Voices at the Same Gain
¾ Condenser microphones of the same serial number of thesame company were used.

¾ The air conduction voice was collected in the distance of

5cm from the mouth and the flesh conduction voice wassampled with the NAM microphone of the OCMSS type.
¾ Right and left tracks were set with the stereo at the same
output level and the same amplification rate.

OCWSS

Repeated TSP Signals

Air
NormalNormalWhisper
SpeechSpeech
NAM

NAM

TMSS

50cm

Flesh

Normal Microphone

NAM Microphone5

Stereo Microphone
Amplifier

61

NAM

Whisper
Air Conduction

30000

300000Air Conduction

0Average of differences of each frame of power-300005.98dB Flesh Conduction

30000

30000

00-30000-30000

Flesh Conduction

7Normal Speech
30000

8

NAM and Background Repeated TSP Sound
30000

Air Conduction

00

Average of difference of each frame of power-30000-3000030000

10.18dB Flesh Conduction

30000

00-30000-300009

BTOS and Background Repeated TSP Sound
30000

Air Conduction

Flesh Conduction

10Pay attention to the ratio of amplitudes of a target signal and the noise signal.

Evaluation of NAM microphonesby HMM Recognition Rates

Air Conduction

0-30000
30000

Flesh Conduction

020K Dictionary-30000

Comparison of NAM recognition rates of soft silicon type and stethoscope type11

Pay attention to the ratio of amplitudes of a target signal and the noise signal.

122

NAM recognition accuracy
according to microphones

BTOS recognition accuracy
according to microphones
BTOS
100

9595

9090

8585
Accuracy

Accuracy

NAM
100

80

80

75

75

70

70

65

65
60

60
1

2

3

45

6

78910

12345

Stethoscopic TypeOCMSS TypeOCWSS Type

6789TMSS Type

Stethoscopic Type

Whisper (Headset)

OCMSS TypeTMSS Type

Normal Speech (Headset)

1314

Variety and Allocation of the Samples

Aural Comprehension Test Using Soft
Silicone Type NAM Microphonerandom permutationof 12 kinds of records
for each rank

Sentence Utterances
I. 文章（日常的な用件文）
1．会議が始まる前に，携帯電話の電源を切って下さい．
2．11日の同窓会には，葉書とアルバムを持ってきてください．
3．明日のミーティングは，午後７時から第二会議室で行います．
4．お金は昨日の午前中に，指定の口座に振り込みました．
5．帰りにスーパーでチューブ入りのわさびを買ってきてね．
6．私の父は昭和1７年の生まれで，戦後の人間です．
7．書店に注文している本が，明日の夕方に届くはずです．
8．五千円からですと，おつりは247円になります．
9．予約したチケットの料金は，コンビニからでも払えるよ．
10．頭が痛くて熱が出てきたので，今日は学校を休むことにする．
11．犬は飼うなと叱られたので，鳥を飼うことにしました．
12．もう少し明るい場所で，きちんと座って本を読みなさい．

Every testee was
supposed to listen
to each utterance
three times.

Mean
6 Male 41.83 y.o.
6 Female 38.83 y.o.

Single Words
II. 意味単語（日常的なものからやや抽象的なものまで）
1．腕時計 2．カーテン 3．爪切り 4．弁護士 5．あじさい 6．双子座
7．模擬テスト 8．上流社会 9．図書館 10．町並み 11．街路樹 12．コーヒー
Meaningless Words
III. 無意味単語（ひらがなにして3〜4文字程度の無意味な単語）
1．かがら 2．むぶぷ 3．のとど 4．えほしゃ 5．うふに 6．ねっけ
7．かーちゅ 8．りょっき 9．さーじつ 10．ほびゅぱ 11．ちしじ 12．なだた

15

Sampling Rate and Aural
サンプリングレートによる人間の聴覚による認識率の差
Comprehension
Accuracy

100%

10Iterative MLLR (400 utterances)

Iterative MLLR (400 utterances)

CodeNA_ST_08 NAM
NA_ST_16 NAM
BT_ST_08 BTOSBT_ST_16 BTOS
NA_OC_08 NAM
NA_OC_16 NAM
BT_OC_08 BTOSBT_OC_16 BTOS
WS_HS_08Whisper
WS_HS_16Whisper
NS_HS_08 Normal Speech
NS_HS_16 Normal Speech

Sensing Device
Stethoscopic NAM Mic
Stethoscopic NAM MIc
Stethoscopic NAM Mic
Stethoscopic NAM Mic
Soft Silicone NAM Mic
Soft Silicone NAM Mic
Soft Silicone NAM MIc
Soft Silicone NAM Mic
Headset Mic
Headset MIc
Headset Mic
Headset Mic

Sampling Rate
8KHz
16KHz
8KHz
16KHz
8KHz
16KHz
8KHz
16KHz
8KHz
16KHz
8KHz
16KHz

16

Aural Comprehension Accuracy ofSentence Utterances (NAM)

95％confidence intervalNS
人間の聴覚によるN
AM発声文章認識率
NS
＊

＊

90%

＊

100%

80%

90%
80%
70%

60%
Accuracy

Accuracy

70%

50%
40%

60%

Control :Air Conducted Whisper

50%
40%
30%

30%
20%

8 16

8 16

8 16

8 16

8 16

8 16

20%

Headset Microphone (Normal Speech)

10%Soft Silicone Nam Microphone

0%
10%0%

1st time
Stethoscopic NAM
Microphone （NAM)

Soft Silicone NAM
Microphone （NAM)

Stethoscopic NAM
Microphone （BTOS）

Soft Silicone NAM
Microphone （BTOS)

Headset Microphone(Whisper)Headset Microphone(Normal Speech)

8KHz

57.48%

89.10%

88.89%

96.79%

97.65%

95.30%

16KHz

45.51%

90.17%

83.33%

98.29%

95.94%

98.71%

2nd time

NAM 聞き取り回数

3rd time
1st*

2nd*

Stethoscopic NAM Microphone

39.42%

14.82%

54.81%

15.75%

Soft Silicone NAM Microphone

78.20%

11.39%

94.87%

5.82%

Headset Microphone (Whisper)

91.67%

5.91%

99.04%

1.51%

Stethoscopic NAM Microphone
Soft Silicone Nam Microphone

17

Stethoscopic NAM MicrophoneHeadset Microphone (Normal Speech)

1st time
39.42%
78.20%

91.67%

3rd*Total*

60.26%

14.09%

50.68%

8.45%

95.83%

5.41%

88.86%

4.83%

99.68%

0.78%

96.68%

2.14%

2nd time
54.81%
94.87%

99.04%

3rd time
60.26%
95.83%
99.68%

18

3

Aural Comprehension Accuracy ofSentence Utterances (BTOS)

Aural Comprehension Accuracyof Single Word (NAM)
人間の聴覚によるNAM発声の単独単語認識率

人間の聴覚によるB
NSNSNS TOS発声文章の認識率

＊

＊

＊
100%

100%

90%

90%

80%

80%
60%

Control :Air Conducted Normal Speech

50%
40%
30%

AccuracyAccuracyControl :Air Conducted Whisper

70%70%

60%
50%
40%30%

Headset Microphone (Whisper)

20%

20%
10%0%

Soft Silicone NAM Microphone0%
1st time

Times of Listening
BTOS

*

2nd*

78.52%

12.24%

87.82%

9.40%

Soft Silicone NAM Microphone

93.91%

78.52% 5.19%

5.19%

99.36%

1.00%

91.99%
93.91%8.32%

99.03%

1st time

Headset Microphone (Normal Speech)

Soft Silicone NAM Microphone

Headset Microphone (Normal Speech)

Meanless Word

3rd time
1stStethoscopic NAM Microphone

Stethoscopic NAM Microphone

Stethoscopic NAM Microphone
Word

Stethoscopic NAM Microphone
2nd time

Soft Silicone NAM Microphone

10%

Headset Microphone (Normal Speech)

91.99%

3rd*Total*

91.99%

6.17%

85.58%

5.44%

Stethoscopic NAM Microphone

44.44%

6.94%

99.36%
87.82%

99.36%

1.00%

97.35%

1.82%

Soft Silicone NAM Microphone

80.56%

11.11%

1.00% 99.36%
100.00%0.00%

96.85%

2.82%
99.36%

Headset Microphone (Whisper)

95.83%

47.22%

2nd time

Word

3rd time
91.99%

99.03%

100%

19

Aural Comprehension Accuracyof Single Word (BTOS)
人間の聴覚によるBTOS発声の単独単語認識率

Meanless Word

20Conclusion¾ The bandwidth of the NAM microphone has improved by

100%
90%
80%
単語
認識精度70%Control :Air Conducted Normal Speech

60%
50%
40%
30%

Headset Microphone (Normal Speech)

20%
Soft Silicone NAM Microphone

10%0%Stethoscopic NAM Microphone
Word
Mealess Word
Word

Mealess Word

Stethoscopic NAM Microphone

65.28%

26.39%

Soft Silicone NAM Microphone

94.44%

45.83%

Headset Microphone (Normal Speech)100%

97.22%

21

using soft silicon for the sound medium compared withstethoscopic type.
¾ The NAM microphone using soft silicon for the soundmedium can sample expanding target voice signal byabout 55-10dB and suppressing air conduction noise
signal to low.
¾ The HMM recognition accuracy of NAM and BTOS has
improved with soft silicon type NAM microphonecompared with stethoscopic type.
¾ The catching sentences of NAM and BTOS accuracy by
the person has improved with soft silicon type NAM
microphone. However, the catching rate of ameaningless word was extremely low.

22ABSTRACT: The bandwidth of the NAM microphone has improved by using soft
silicon for the sound medium compared with stethoscopic type. With softsilicone type NAM microphones we can sample expanded target voice signal
by 5-10dB, suppressing air conduction noise signal to low by theexperiment of synchronous stereo sampling of air and flesh conductedvoices at the same gain. The HMM recognition accuracy of NAM andBTOS has improved with soft silicon type NAM microphone compared withstethoscopic type. Aural comprehension test showed that accuracy of catchingsentences of NAM and BTOS by 12 testee has improved with soft silicon
type NAM microphone almost as high as that of air conducted voices.
However, the catching rate of a meaningless word was extremely low.

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