Insights from industry

Building the Exact Acoustic Enclosure for Your Instrument

Cory Roush, Production & Quality Control Manager from Herzan, talks to AZoM about the importance of building an acoustic enclosure for your instrument to help recieve the maxiumum resolution from the data.

Please can you tell us about the different acoustic enclosures that Herzan develop and how they can benefit research and labs around the world?

Herzan acoustic enclosures are designed to provide instrument users with the quietest operating environment possible, allowing them to receive maximum resolution from their measurement data.

While we have many standard solutions supporting a wide range of instruments (i.e. workstation, desktop, and SEM enclosures), custom enclosures are our specialty and what differentiates us from other enclosure manufacturers who are unable to design and manufacture one-off enclosures to individual specification at a reasonable price.

Workstation acoustic enclosures, like the AEK-2002, offer a complete working environment for instrument users needing maximum acoustic isolation.

Desktop acoustic enclosures, like the Silencer, are designed for space constrained applications needing broadband acoustic damping. SEM enclosures are unique in that they are designed to address individual needs of electron microscope users, including accessibility, performance, and functionality customizations.

Whether a customer receives a standard or custom enclosure from Herzan, they can feel assured the same guiding principles will apply to their enclosure: maximum acoustic isolation performance and maximum utility for their research needs.

Desktop Acoustic Enclosure for An Optical Table

Figure 1. Desktop Acoustic Enclosure for An Optical Table

Why are custom enclosures necessary for research applications?

Acoustically sensitive instrumentation have natural frequency resonances that can be excited under certain environmental conditions. When the natural frequency resonances are excited, the resolution of data and image quality suffers, limiting the capability and functionality of the instrument.

Custom enclosures help solve this problem by using unique acoustic damping layers to isolate specific frequencies of interest.

In addition to damping acoustic noise at specific frequencies, custom enclosures can be modified to include specialized features that address environmental, accessibility, and form factor requirements defined by the end user.

Some popular modifications include:

  • Temperature Stability (environmental)
  • Improved Acoustic Damping Performance at Individual Frequencies (performance)
  • Removable Access Doors (accessibility)
  • Custom Sizes and Shapes (form factor)
  • Custom Cable Clamps and Feedthroughs (accessibility)
  • Gas Purge (environmental)
  • And more

Desktop Acoustic Enclosure with Active Vibration Isolation Table Upgrade

Figure 2. Desktop Acoustic Enclosure with Active Vibration Isolation Table Upgrade

Please explain how the Herzan Acoustic Isolation blocks noise? What is the best way to reduce noise generation?

Herzan enclosures utilize a proprietary layering technique that addresses high and low frequency acoustic noise, delivering significant acoustic attenuation (up to 60 dB) over a broad frequency spectrum.

Herzan enclosures comprise of variable density layers and material compositions, intended to offer the most effective and affordable acoustic isolation performance possible.

Higher-density materials address lower-frequency acoustic noise, while lower-density materials address higher-frequency noise.

Using a combination of these different layers is how Herzan’s enclosures provide the quietest operating environment for sensitive instruments and applications.  

The best way to reduce noise production is to isolate the source of noise from the sensitive piece of equipment.

Pumps, chillers, and other loud equipment often have to share the same lab space as AFMs, SEMs, and other sensitive instrumentation.

By enclosing loud equipment from letting sound out or by enclosing sensitive instrumentation from letting sound in, users can have a multifaceted approach to resolving the impact of acoustic noise on their research.

What role does shape and form play in how acoustic noise is absorbed, reflected and damped?

The perfect design scenario for an acoustic enclosure is to have an enclosure comprise of unequal-sized walls to minimize standing waves, however, that design configuration is not practical and often conflicts with other requirements of the end user.

Most of the time, enclosures are designed around particular instrument configurations to provide uniquely tailored performance and accessibility.

While Herzan has a collection of standard enclosures to choose from, it is common for researchers with unique instrument types to partner with Herzan to design a bespoke enclosure that resolves individualized research requirements.

When designing a new enclosure and optimizing how acoustic noise is absorbed, it is important to ensure there are no large, unstiffened surfaces within the enclosure, as these surfaces allow for greater low-frequency acoustic noise to be transmitted within the enclosure at higher amplitude values.

Resolving this is achieved through stiffer exterior walls or adding stiffeners to the interior of the large, unsupported area.

Silencer Desktop Acoustic Enclosure

Figure 3. Silencer Desktop Acoustic Enclosure

What specific frequencies can the acoustic isolation be tailored to?

Depending on the manufacturer, the range of acoustic noise being isolated by enclosures begins around 100 Hz, up to 5,000 Hz.

With regards to Herzan enclosures, the design is to have lower-frequency noise being attenuated (50 Hz or less) in addition to the higher frequency ranges.

This improved performance is achieved through its specialized layering techniques. Beyond 5,000 Hz, enclosures tend to offer fairly uniform performance.

Majority of instruments supported by Herzan enclosures require isolation within the 50 – 5,000 Hz frequency range, but we often work closely with instrument manufacturers and end users who have particular sensitivities at individual frequencies to tailor the material lining of the enclosure to focus its isolation performance at that frequency.  

Acoustic Isolation Performance Graph of the AEK-2002

Figure 4. Acoustic Isolation Performance Graph of the AEK-2002

What optimal design considerations help improve the performance of the enclosure?

First and foremost, acoustic enclosures need to be air-tight to ensure acoustic noise is not being introduced directly inside the enclosure.

Acoustic noise is multi-directional, only needing partial access to be disruptive. Without an air-tight seal, the instrument becomes susceptible to the ambient noise conditions of the environment, rendering the enclosure less effective than intended.

Second, it is important to have the right acoustic layering technique employed within the enclosure to effectively address the sensitive frequencies of the instrument.

Not all instruments are made the same, which is why having the right layering configuration can have a big impact on the overall performance of the instrument.

Third, creating sufficient access around the instrument is key, as the function of an enclosure is not to only offer a quiet operating environment, but to also allow the end user to operate their instrument unencumbered.

Having an inaccessible instrument inside an enclosure will often require more time from the researcher when having to make changes, which is time that could have been spent performing his or her research.

What are the differences between the Workstation Acoustic Enclosure and the Desktop Acoustic Enclosure?

The differences between workstation and desktop acoustic enclosures reside within their intended purpose. Workstation acoustic enclosures offer users a standalone solution, focused on maximum performance and utility based on the requirements of their instrument.

These enclosures can be easily customized to add complementary features and are often the highest performing enclosures made by Herzan.

Desktop acoustic enclosures are intended to offer users a more compact solution when space is either limited or unavailable.

Desktop enclosures are often fixed to existing benchtops or optical tables, offering an easily integrated solution for instruments needing broadband acoustic control.  

NanoVault Workstation Acoustic Enclosure

Figure 5. NanoVault Workstation Acoustic Enclosure

What are the best practices for acoustic enclosure users?

A well designed acoustic enclosure should have little variance in terms of its use, but there are some key tips for users owning and operating a Herzan enclosure that will maximize its utility.

First, when performing a precise measurement with your instrument, make sure the front door is securely closed and latched, creating an air-tight seal.

All Herzan enclosures come standard with air-tight latching hardware and it is important these latches are used during the measurement process. Second, when installing/uninstalling cables, make sure the cable clamps provided with the enclosure do not have significant gaps where the cables are inserted.

The foam provided with every cable clamp contours to the diameter of the cable, but when larger diameter cables are used, it is important to verify the interior of the enclosure is not exposed.

Third, if a vibration isolation table is used in conjunction with a workstation enclosure, it is important to have the enclosure rest on its levelling feet and not its caster wheels, for improved rigidity and stability.

Herzan also has a list of best practices for its acoustic enclosures and all other products on its website (link here: http://www.herzan.com/resources/best-practices.html).

Where can our readers go to find out more?

Herzan has a variety of resources available to AZO readers on its website, including articles detailing solutions for specific applications, instruments, and research methodologies. Herzan also distributes its latest news and product developments through an email newsletter—Herzan Happenings.

To sign up and receive the newsletter, email [email protected] and you will be enrolled on the next mailer.

About Cory Roush

Production & Quality Control Manager / Product Designer  

Cory Roush

Cory joined Herzan in May of 2011 as the Production and Quality Control Manager. He is in charge of leading production for Herzan products and ensuring all products delivered to customers meet Herzan’s standard of excellence.

Cory is also involved in designing new and custom products, working closely with customers to better understand their requirements and delivery top customer satisfaction.

Prior to joining Herzan, Cory worked on high-performance street bikes as a welder and fabricator in San Luis Obispo, California (his hometown).

Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of AZoM.com Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.

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