Questions tagged [noise]

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Releasing compressed air with the loudest pop

Due to the dry summer I've been thinking about theory of making cracker/banger without fire. Would connecting a nozzle (de Laval?) to quick release valve from small cylinder with the pressurised air ...
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Freestanding wood frame inside masonry shell for noise?

I'm a lay neighborhood advocate, not an engineer. Proposed is a three-storey multi-family housing project adjacent to an airport. A concern is that noise pollution will create higher tenancy turnover, ...
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Calculate Noise spectral density and rms noise from voltage signal data

I'm trying to come to grips with calculating noise figures starting from a generic electrical signal but I feel like even if the concept is theoretically in my head I'm not able to move forward. I ...
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How loud can an induction hob be?

People that are cooking food with induction will occassionally encounter loud noises from the hob. There can occur a high-pitched whining sound when heating the pots and/or pan. As I searched the ...
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What to do with the high dv/dt on bridge H?

I have an H bridge, with a 540V DC link. There is a high level of noise induction across the board (even though all circuits and sources are isolated). Bridge H has drives that provide dual power (+...
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1 vote
2 answers
188 views

How do I remove outliers in measured sound pressure levels data?

I have measured sound pressure levels (24 h sampling at 25600 Hz) data for many days. The focus of measurements was on road noise, which is a dominant source of noise in the measurement setting. ...
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1 answer
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Active noise cancelling headphones - How fast does a digital signal processor have to be to perfectly cancel out noise with an inverted signal?

How fast does a digital signal processor have to be to perfectly cancel out noise with an inverted signal? Is it possible for a digital signal processor react so fast?
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1 answer
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How to add a Gaussian noise signal with zero-mean in a given data set?

I have a real-time velocity measurement data set in a excel (.xlsx) file. I want to add the Gaussian noise signal with zero mean in this real-time data to create three set of pseudo measurements. ...
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Active noise canceling for CNC enclosure

this is my first post here! I wanted to share my ideas for this and get some input on them. My parents were kind enough to let me put a cnc machine in the loft. (shapeoko 3 xxl) In order to make them ...
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2 votes
2 answers
83 views

How to convert the velocity field to a pressure field for obtaining the sound level?

I am studying jet mixing noise and I am given a velocity field, with $V_x$, $V_y$, $V_z$ in the Cartesian coordinates. I wanted to know if there is a method by which I could find some information ...
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Understanding the RMS noise for a given bandwidth

I would like to ask a technical question regarding the current source Keithley Series 2400 Model 2450. I am looking for a high stability current source capable of feeding some Hall probes with a ...
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3 answers
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How do AC/DC Adapters (Wall Wart) prevent AC Noise Coupling to DC?

I am wondering if AC noise (EMI) gets coupled to the DC side of the AC/DC adapter, what are the design methods used to isolate AC noise getting coupled to DC output in an AC/DC adapter. What are the ...
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allan-variance noise terms of MEMS accelerometer

Specific noise terms are given in datasheets of MEMS sensors. In example the specification of accelerometer contains information about random walk and in some cases the bias instability. Both ...
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2 votes
3 answers
150 views

Why does audio equipment buzz/humm when a long signal cable is used and how do I eliminate it?

I have two 5.1 speaker sets, one in the front and one in the back of my living room. I have connected them together with an "audio wire" (non-shielded unfortunately) that's 12 meters in length. Since ...
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1 answer
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Linear actuator with low vibration and low noise

Which kinds of linear actuators offer the lowest levels of noise and vibration? I am looking for an actuator with these properties that can push a load vertically on the cm scale. Velocity, accuracy ...
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1 answer
133 views

How do I calculate hourly LAeq sound pressure level using 1-mint LAeq values?

I have continuous A-weighted sound pressure level (SPL) values at 1 minute time resolution (LAeq,1min). I would like to calculate ...
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1 answer
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Noise sensitivity transfer function

Consider we have a second order system (plant) described by the following transfer function: $$ P(s) = \frac{b_0}{s^2+a_1*s+a_2} $$ which is controller by a PD-controller: $$ C(s) = K_p+K_ds $$ ...
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1 vote
2 answers
482 views

How to reduce oscillations (rapid changes of control signal) when controlling a real system, which occur due to noise in measurement from sensors?

I have a real mechanical system (ball & beam) which I want to control. The system is approximated by the second order transfer function: $$ T(s) = \frac{b_0}{s^2+a_1s+a_2} $$ and in state-space ...
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1 vote
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24 views

Meaning of SNR in Instrument Specifications

I am evaluating the specifications of an FTIR instrument (Bruker Vertex) and came across the following statements/items: Signal-to-Noise 5 sec sample, 5 sec reference: >10,000:1 (<4.34 x 10-5 ...
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1 vote
1 answer
60 views

Sound level emissions (IEC 60704-1) spectrum?

I have a very noisy air conditioner that have a 10kHz peak at 75 dB, the rest (fan/compressor/pump) are under the regulation limit. I would like to understand what is the measurement spectrum. I ...
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