Acousteen, Herman Steeneken 1 Past, Present and Future of STI Herman J. M. Steeneken ()
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Transcript of Acousteen, Herman Steeneken 1 Past, Present and Future of STI Herman J. M. Steeneken ()
1Acousteen, Herman Steeneken
Past, Present and Future of STI
Herman J. M. Steeneken (www.steeneken.com)
2Acousteen, Herman Steeneken
Past: STI (1971, 1980), Envelope Spectrum (1972), MTF (1975), RASTI (1979), prediction by ray-tracing(1981), IEC 60268-16 (1988, 1998)
Present: Revised STI (1992, 1999, 2002), STIPA (2001), IEC 60268-16 (2003), ISO 9921 (2003)
New and Future: Binaural STI, improvement measurement STI from speech signal, non-native speech, vocoders
3Acousteen, Herman Steeneken
Signal-to-Noise ratio !!!
4Acousteen, Herman Steeneken
Assessment Methods
• Subjective assessment with subjects (speakers
and listeners): representative, limited
reproduction, no diagnostics, laborious
• Objective assessment based on physical
properties (measurements): reproducible,
diagnostic, fast
• Objective methods allow prediction of system
performance: design tool
5Acousteen, Herman Steeneken
Speech and Noise
6Acousteen, Herman Steeneken
Speech envelope function and envelope spectrum
7Acousteen, Herman Steeneken
Spatial line frequency equivalent to MTF
8Acousteen, Herman Steeneken
Distortion of Speech Envelope
9Acousteen, Herman Steeneken
Dynamic measurement of SNR
10Acousteen, Herman Steeneken
Matrix for seven MTF’s
1 Hz
X
3 Hz
10 Hz
11Acousteen, Herman Steeneken
CALCULATION of STI
12Acousteen, Herman Steeneken
Calculation scheme
13Acousteen, Herman Steeneken
Frequency weightings (various studies)
octave-band centre frequency (Hz)
freq
uenc
y-w
eigh
ting
fact
or
0.0
0.1
0.2
0.3
0.4
0.5
125 250 500 1k 2k 4k 8k
nonsense syllables (Pavlovic et al. 1984, ANSI S3.5)PB-words (Steeneken et al. 1980, IEC 60268-16)initial consonants (Steeneken, 1992)vowels, (Steeneken, 1992)
14Acousteen, Herman Steeneken
Redundancy with image detection
15Acousteen, Herman Steeneken
Frequency weightings (CVC words)
octave-band centre frequency (Hz)
fre
qu
en
cy-w
eig
htin
g fa
cto
r
0.0
0.1
0.2
0.3
0.4
0.5
125 250 500 1k 2k 4k 8k
CVC words male speech female speech
MTI + .... + )MTIMTI(
- MTI + )MTIMTI( - MTI = STI
77322
2221111r
16Acousteen, Herman Steeneken
Relation Noise and Band-pass limiting
STI r
CV
C-w
ord
scor
e (%
)
1
2
3
4
5
6
78
9
10
11
12
13
14
15
16
17
18
0
20
40
60
80
100
0.0 0.2 0.4 0.6 0.8 1.0
male speech
S.d.= 4.4%
Male speech
17Acousteen, Herman Steeneken
Listening test with four subjects
18Acousteen, Herman Steeneken
Embedded CVC words:
versta des overen nu fijs uithet woord zek eindenoteer lal punt
“Semi random” combinationof:
17 initial consonants15 vowels11 final consonants
19Acousteen, Herman Steeneken
Relation AGC and echoes
S.d.= 6.9 %
Male speech
STI r
CV
C-w
ord
scor
e (%
)
33
34
35
36
37
38
39
4041
42
43
44
44
45
46
47
48
49
50
51
52
53
54
55
0
20
40
60
80
100
0.0 0.2 0.4 0.6 0.8 1.0
male speech
20Acousteen, Herman Steeneken
Qualification of STI (Acustica, 1984)
21Acousteen, Herman Steeneken
Performance cabin public address
22Acousteen, Herman Steeneken
Iso-STI contours
23Acousteen, Herman Steeneken
Effective gain of a PA-system
24Acousteen, Herman Steeneken
Field measurement
25Acousteen, Herman Steeneken
Full STI (STI-14 and limited modulation frequency range STI-3)
STI-14
• Seven octave bands
• 14 Modulation frequencies
• Random envelope for octaves not under test
STI-3
• Seven octaves
• 3 Modulation frequencies (1.0, 3.15, and 10 Hz)
• Random envelope for octaves not under test
26Acousteen, Herman Steeneken
RASTI (Room Acoustics STI,1979)
Only for person-to-personcommunication assessment
Two octave bands(500Hz and 2 kHz)
Complex envelope(4 and 5 mod. freq.)
see Acustica 1984, IEC 60268-16
27Acousteen, Herman Steeneken
STI-PA (STI Public Address, 2001)
Assessment of Public Address
including: acoustic environment,band-pass limiting, overload dis-tortion
Seven octave bands (125 Hz and 250 Hz merged)
Complex envelope (2 simultaneous modulation frequencies per band)
see IEC 60268-16
28Acousteen, Herman Steeneken
Future
• Binaural STI
• Improvement using Speech as test signal
• Non-native talkers and listeners
29Acousteen, Herman Steeneken
Future: Binaural STI (I)
Use artificial head and perform
simultaneous measurement on both ears
Select highest performance (best ear
selection)
Use cross correlation approach for 500,
1000, and 2000 Hz.
30Acousteen, Herman Steeneken
Future: Binaural STI (II)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
10
20
30
40
50
60
70
80
90
100
22
27
33
39
37
3 7
2523
19
417
28
35
15
13
9
1
31
38
5
18
32
20
26
6
1116
2
29
24 14
10
8
21
12
3634
30
STI
CV
C w
ord
scor
e (%
)
monaural CVC vs STIMean ear STIBinaural STI
31Acousteen, Herman Steeneken
Future: improvement Speech Signal as test signal
32Acousteen, Herman Steeneken
Future: non-native talkers and listeners
L1 L2
-12 -6 0 6 12 0
10
20
30
40
50
60
70
80
90
100
Speech-to-noise ratio (dB)
spee
ch in
telli
gibi
lity
(% c
orre
ct)
resp
onse
s)
0.10 0.300
0.50 0.70 0.90 STI
33Acousteen, Herman Steeneken
Conclusions
• STI predicts the speech intelligibility for many
types of distortion: noise, band-pass limiting,
non-linearity's, temporal, vocoding, non-native
speech, and binaural hearing.
• Improvements (measuring methods or scope) of
STI will not change the qualification ranges.
• STI is an international standardized method
(ISO9921, IEC 60268-16) and used for many
national standards.