b*******2
发帖数: 2121 | 1 一般来说,The lowest amplitude that a healthy human ear can detect is 20mPa.
那么对于一个microphone 来说,怎么来看它能检测的最小的amplitude? specs 上哪个
参数是对应的? 怎样换算成 单位Pa 呢?
万分感谢! | E*****a
发帖数: 757 | 2 找一个datasheet来看看
.
【在 b*******2 的大作中提到】
: 一般来说,The lowest amplitude that a healthy human ear can detect is 20mPa.
: 那么对于一个microphone 来说,怎么来看它能检测的最小的amplitude? specs 上哪个
: 参数是对应的? 怎样换算成 单位Pa 呢?
: 万分感谢!
| b*******2
发帖数: 2121 | 3 我现在有两个mic在用,第一个是很普通很便宜的一般mic,第二个是ultrasonic的.两个
datasheet在网上分别可以看到如下链接:
http://media.digikey.com/pdf/Data%20Sheets/Horn%20Industrial%20PDFs/EM1050-38.PDF
http://www.knowles.com/search/prods_pdf/SPM0404UD5.PDF
为了方便,我把两个mic的简要specs 截图附上.
多谢指教!
【在 E*****a 的大作中提到】
: 找一个datasheet来看看
:
: .
| z*****n
发帖数: 7639 | 4 The sensitivity already told you the minimum sound
pressure the mic can pick up. For the 1st one it is
-38dB when input is 1kHz 1Pa, and 1Pa means
20log(1Pa/20uPa ) = 94dB. So the it can pick up
a minimum sound (at 1kHz) 94-38 = 56dB which is
20uPa*10^(2.8) = 12.62mPa.
The 2nd one is 4dB more sensitive.
【在 b*******2 的大作中提到】
: 我现在有两个mic在用,第一个是很普通很便宜的一般mic,第二个是ultrasonic的.两个
: datasheet在网上分别可以看到如下链接:
: http://media.digikey.com/pdf/Data%20Sheets/Horn%20Industrial%20PDFs/EM1050-38.PDF
: http://www.knowles.com/search/prods_pdf/SPM0404UD5.PDF
: 为了方便,我把两个mic的简要specs 截图附上.
: 多谢指教!
| z*****n
发帖数: 7639 | 5 It is not 20mPa, it is 20uPa.
.
【在 b*******2 的大作中提到】
: 一般来说,The lowest amplitude that a healthy human ear can detect is 20mPa.
: 那么对于一个microphone 来说,怎么来看它能检测的最小的amplitude? specs 上哪个
: 参数是对应的? 怎样换算成 单位Pa 呢?
: 万分感谢!
| b*******2
发帖数: 2121 | 6 thanks. you're right. corrected.
【在 z*****n 的大作中提到】
: It is not 20mPa, it is 20uPa.
:
: .
| b*******2
发帖数: 2121 | 7 非常感谢你的解答! 对下面这句有点疑惑:为什么这个就是可以pick up 的最小
pressure?
"So the it can pick up: a minimum sound (at 1kHz) 94-38 = 56dB"
根据定义,A microphone’s sensitivity (pressure sensitivity) is defined as
the voltage generated in response to a certain pressure input. (units V/Pa,
then converted to dB).
比如 -38dB means S=10^(-38/20)=12.6mV/Pa. 意思是对于1Pa 的pressure 会产生 12
.6mV 的电压...
好像sensitivity 的定义并没有说它和mic 能检测到的最小pressure 有何关系.
另外,我在microphone handbook里看到下面这样一句:
The cartridge thermal noise specification provides the lowest measurable
sound pressure level that can be detected above the electrical noise,
inherent within the microphone.
感觉好像是这个CTN 在define 最小可测 pressure...
不知道我的理解正确吗?
请指正. 多谢!
【在 z*****n 的大作中提到】
: The sensitivity already told you the minimum sound
: pressure the mic can pick up. For the 1st one it is
: -38dB when input is 1kHz 1Pa, and 1Pa means
: 20log(1Pa/20uPa ) = 94dB. So the it can pick up
: a minimum sound (at 1kHz) 94-38 = 56dB which is
: 20uPa*10^(2.8) = 12.62mPa.
: The 2nd one is 4dB more sensitive.
| z*****n
发帖数: 7639 | 8 no, there are two ways to define the sensitivity:
The international way is to use mV/Pa to indicate the sensitivity,
and old-fashioned US way to use a decibel referring 1V/Pa as 0dB.
In your first spec. I think it is the second way. So, it is
not related to the minimum pressure it can detect. The minimum
pressure is only a matter of the Noise floor of your circuit,
or the SQNR of your A/D convertor.
Sorry.
,
12
【在 b*******2 的大作中提到】
: 非常感谢你的解答! 对下面这句有点疑惑:为什么这个就是可以pick up 的最小
: pressure?
: "So the it can pick up: a minimum sound (at 1kHz) 94-38 = 56dB"
: 根据定义,A microphone’s sensitivity (pressure sensitivity) is defined as
: the voltage generated in response to a certain pressure input. (units V/Pa,
: then converted to dB).
: 比如 -38dB means S=10^(-38/20)=12.6mV/Pa. 意思是对于1Pa 的pressure 会产生 12
: .6mV 的电压...
: 好像sensitivity 的定义并没有说它和mic 能检测到的最小pressure 有何关系.
: 另外,我在microphone handbook里看到下面这样一句:
| b*******2
发帖数: 2121 | 9
如果排除其他电路不考虑,只看mic 本身, 是哪个mic的参数limit 它自身的the
minimum pressure detection 呢?
是上面specs 上的 S/N 吗? 还是我前文提到的 CTN? 不知如何换算?
多谢啊!
【在 z*****n 的大作中提到】
: no, there are two ways to define the sensitivity:
: The international way is to use mV/Pa to indicate the sensitivity,
: and old-fashioned US way to use a decibel referring 1V/Pa as 0dB.
: In your first spec. I think it is the second way. So, it is
: not related to the minimum pressure it can detect. The minimum
: pressure is only a matter of the Noise floor of your circuit,
: or the SQNR of your A/D convertor.
: Sorry.
:
: ,
| z*****n
发帖数: 7639 | 10 according to your 2nd picture. It should be, which
is related to 0dB/1V sound pressure.
【在 b*******2 的大作中提到】
:
: 如果排除其他电路不考虑,只看mic 本身, 是哪个mic的参数limit 它自身的the
: minimum pressure detection 呢?
: 是上面specs 上的 S/N 吗? 还是我前文提到的 CTN? 不知如何换算?
: 多谢啊!
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