Tag: sound

The Acoustics of Sonic Booms

Sonic booms are something that most people will have heard at some point in their lives, perhaps from planes passing by at an airshow, or from a bull whip (yes, the tip travels faster than the speed of sound!), but what exactly are they? and how do they produce such an incredible noise? This posts explores the acoustics of sonic booms.

A Guide To Hearing Protection

In many cases the use of hearing protection is essential for protecting yourself from loud and potentially dangerous noise, but there are many different types of hearing protection available for many different scenarios. Knowing which type of protection is the most appropriate for you is important, the guide below should help you to make a more informed decision about which to be using and when.

The Basics Of A Sound Level Meter

The modern sound level meter is a powerful tool with many useful functions, but what are the most important things to know? This post aims to act as a simple to follow guide.

Natural Hearing Protection: Hands?

Have you ever covered your ears with your hands to protect yourself from loud noise? That’s the closest to natural hearing protection that we’ve got, but just how much does it reduce the sound pressure level reaching your ear? And what’s the best method? This experiment aims to find out.

How Loud Is Too Loud?

The World Health Organisation states that loud noise is the single biggest preventable cause of hearing loss in the UK. Due to advances in portable media player technology, users are now able to store and play music for much longer. Due to this, there is a huge potential risk for overexposure to noise using these devices. It is now estimated that over 4 million young people in the UK are suffering with the effects of noise induced hearing loss from listening to amplified music in the UK.

Recovery of sound from video

Research carried out by the Massachusetts Institute of Technology, along with Microsoft and Adobe, has been used to extract audio data from video by analysing the tiny, imperceptible vibrations that occur in objects when they are subject to a sound.

Cupped Hand Amplification

It may be common knowledge that cupping your hand around your ear can help to amplify sounds, making speech more intelligible or making a distant whisper just a little louder, but what does the hand do to the ear to make it easier to hear these sounds?

Malta’s Hypogeum of Ħal-Saflieni

The UNESCO World Heritage Site at Paola, Malta has special significance due to its remarkable acoustic properties. The Hypogeum of Ħal-Saflieni is an underground cave system covering around 500m² on 3 levels, with various inter-connecting corridors and passageways that lead to a number of small chambers, built between 3000-2500BC. The cave system was re-discovered in 1902 and since then there has been particular interest in one of the rooms, named the “Oracle Chamber”. The space is said to amplify voices dramatically, with certain frequencies resonating enough to be felt through the body.

The Acoustic-Optical Microphone

A relatively new development from VocalZoom, a voice communications company based in Israel, involves the use of a combination of microphone and optical sensor to drastically improve voice communication in noisy environments.

Named “SEEON” or Speech Enhancement Electro Optical Microphone, the new technology aims to offer 20-40dB of noise reduction in situations such as high volume industrial workplaces, busy cityscapes and parties.

Tutorial: Measuring Reverberation Time

The reverberation time of a room has a distinct effect on its suitability for different tasks, in this tutorial we will look at the different methods of measuring reverberation time and what the results can show us.

The first step in carrying out a reverberation time measurement is choosing the method. There are a number of different methods available to us however some will require specialist equipment that the average person will not have access to (look out for follow up tutorials for these!). The simplest method involves creating and recording an impulse response.