How loud is your neighborhood?—Community Noise

Posted by:

Nearly everyone has a story about annoying noises—the roommate who plays music at all hours of the night, the would-be dragsters on the freeway nearby, or the airplanes roaring past overhead. Obnoxious sounds can distract us and disrupt the normal balance of our lives. In severe cases, noise can contribute to increased aggression, hypertension, and stress. Long term effects of high levels of noise exposure include hearing loss, tinnitus (ringing in the ears), sleep disturbance, and increased blood pressure. It ...

Continue Reading →
0

Leq: What does it mean?

Posted by:

Leq (said “L E Q”) stands for Equivalent Continuous Sound Pressure Level, and is one of the most important sound level metrics. It’s nice because it boils a sound level measurement down to one decibel level number. The Leq represents the total sound energy logged over the course of a measurement.

Since the Leq corresponds with the total sound energy, it is a useful way to predict hearing damage threats as well potential noise complaints. As a result, the Leq is ...

Continue Reading →
0

The ABCs of Frequency-Weighting

Posted by:

Like other animals, humans hear different pitched sound differently. Some sounds, such as those in the range of speech or a baby crying, are easy to hear and emphasized by the ear. Other sounds, such as low-pitched rumbling or high-pitched buzzing might be more difficult to hear. In an effort to take these differences into account, acoustics professionals have developed patterns for emphasizing or de-emphasizing sounds at different pitches. In this article, we will discuss these patterns—called frequency weighting curves—and ...

Continue Reading →
0

Are Lpeak and Lmax Different?

Posted by:

Newcomers to the field of acoustics are often overwhelmed by the number of different level metrics used to characterize environmental and community noise. To make matters worse, almost all of these metrics are abbreviated with capital Ls and reported in units of decibels. The purpose of this article is to help distinguish between three of these Ls: Lpeak, Lmax, and Lmin. Of the three, Lpeak is the easiest to understand, so we’ll start there.

Lpeak

Lpeak stands for peak level. The peak ...

Continue Reading →
0

Fast, Slow, and Impulse Time Weighting: What’s the difference?

Posted by:

When it comes to sound level measurements, there are three types of time weighting that you see: Slow, Fast, and Impulse. In this article, we’ll talk about the difference between these ways of weighting and where they came from.

The terms slow and fast weighting go back to the days of analog sound level meters. Analog meters had a needle that would point to numbers on a scale. With differences in manufacturing and design, some of these needles reacted faster than ...

Continue Reading →
2

Calculating Resonant Frequencies

Posted by:

This article continues from the last article, Introduction to Resonance. If you need to review standing waves, nodes, and antinodes, you might want to check out that article first. Otherwise, let’s get right down to business.

How to Find Resonant Frequencies

Remember from the last article that standing waves happen when nodes or antinodes line up with the ends of a rope or pipe. Such standing waves create resonance. The lowest frequency that “fits” on a string or in a space ...

Continue Reading →
0

Intro to Resonance

Posted by:

Gallopin’ Gertie

One of the first acoustics topics most physics classes cover is resonance. Often, physics teachers will show the video clip below of the collapse of the Tacoma Narrows Bridge (also known affectionately as “Gallopin’ Gertie”) to demonstrate the potential effects of resonance.

While the rippling motion of the bridge seems unreal, the physical principle of resonance is quite real. Gaining an ...

Continue Reading →
1

Why Don’t My Noise-Canceling Headphones Block All Sounds?

Posted by:

Calling headphones noise-cancelling can be deceptive. While it is true that noise-cancelling headphones are capable of counteracting some background noises, they are not perfect for all types of noise. In this article we will discuss the inner workings, limitations, and potential tradeoffs of noise-cancelling headphone technology.

All Headphones are Noise Cancelling

Technically all headphones are noise cancelling on some level. Just as putting your hands over your ears blocks incoming sound, any headphone you put on, in, or over your ear will ...

Continue Reading →
0

Megaphones: Heard above the Noise

Posted by:

The megaphone is one of the oldest acoustical devices. People learned early that horn-shaped or cone-shaped tubes could be used to increase the audibility of the human voice. However, it took much longer for humanity to discover exactly how megaphones amplify sound.

A Quick History

Many early civilizations used “speaking horns.” Some Native American leaders used birch bark horns to communicate with large groups. In ancient Greece, actors wore masks with cone-like openings around the mouth which amplified their voices. Many inventors ...

Continue Reading →
0

Preamplifiers: Do I Need One?

Posted by:

What is a Preamp?

A preamplifier (preamp or just “pre” for short) is an electronic component used to condition signals from a microphone or pickup. The output signal from a microphone is generally weak and noisy. If you plugged a microphone directly into an audio interface, the sound would come out distorted and garbled. Not exactly the result you want from your audio system. That’s where preamps come in.

Preamplifiers boost the strength of a signal without significantly degrading its signal-to-noise ratio ...

Continue Reading →
0
Page 1 of 3 123