January 9, 2018    Newsroom

What’s all this noise about Hearing Loops?

As you may have heard, New York City has recently signed into law a requirement for Hearing Loops to be installed in building projects of a certain size, that are funded by the NYC Treasury Department.  Hearing loops are a clever technology that harness the power of electromagnetic waves to directly transmit sound to compatible hearing aids; they assist in amplifying desired sounds and reducing background noise, inconspicuously and inexpensively, in all kinds of situations from large assembly halls to ticket counters.  The technology has been employed in Europe for some time and is starting to gain some traction within the United States. Continue on for more information on the NYC local law and the technology…

Summary of Local Law

Signed into law on 3/17/17, and taking effect this year, Local Law 51 of 2017 amends the New York City charter to require the installation of Induction Hearing Loops in places of assembly where the project is funded solely, or partially by the NYC Treasury. A project would require a hearing loop if the following requirements are met:

1. The project contains a space that is defined as an assembly area by the 2010 ADA Standards. These include spaces that are used for entertainment (concert halls, movie theatres, auditoriums) and civic meeting (public meeting halls and hearing rooms). The Local Law excludes classrooms in schools, outdoor facilities (stadiums, amphitheaters), courthouses, and facilities used to deploy first responders from the definition of assembly area.

2. The project must be a capital project where at least 51% of the construction cost or more than $1M is paid by the city treasury. Projects with a baseline construction cost of $950,000 or greater must comply. This is the cost of construction before the cost of a required hearing loop system. This requirement includes new construction and renovations. Capital projects that involve the construction or renovation of assembly areas not owned by the City are at present exempt.

The Technology

There are three parts to a hearing loop; the audio input, amplifier, and loop aerial. The audio input could be anything from a microphone to a music player. The amplifier takes the audio from the input device processes, and strengthens it, then sends the signal to the loop aerial. The signal travels through the loop aerial, which is a simple copper wire loop and can be received by any compatible hearing device (those with a “T” switch). Normally, hearing aids amplify all sounds, including background noise. Using a hearing loop with a compatible aid allows the listener to receive the sound directly from the audio source and cancels out most background noise.

Hearing loops can be designed for large meeting rooms or be designed small enough to work on a countertop. As a matter of fact, hearing loops already exist in the majority of NYC subway station booths and some NYC Taxis! Figures 1 and 2 show a typical loop set up in an assembly space and the sign that is required to be displayed when a hearing loop is installed and available, respectively.

 

Figure 1 – A perimeter hearing loop for a large room (e.g. special events, places of worship, theatre, etc.), What is a Hearing Loop?, HearingLink.org, 1/26/18

Figure 2 – Signage alerting patrons of the presence of a hearing loop, Hearing Loop, The Hearing Connection, 2/6/18

Design Considerations

Just as any other building system, preparations must be taken during the design to ensure that the audio induction loop is working properly. The international standard IEC 60118-4 exists to ensure that systems are designed to produce uniform, clear sound. The standard addresses obstacles to ideal system functionality including loop positioning, overspill, and interference. Loops need to be positioned so that listeners can comfortably receive sound. If a loop is positioned incorrectly, a listener may receive a sound that is too strong or too weak. Depending on the size of the loop, the sound will be able to “spill” outside of the room and design will need to be modified so that reception is contained to the intended audience. Metal structures and electromagnetic interference from electrical equipment will also affect the loop’s signal strength and quality. With all these factors that can affect the audio loop performance, careful planning must be taken in designing an appropriate loop.

If your project falls within the requirements of Local Law 51 or if you believe that installing a hearing loop would benefit your business, contact us today!

– Mario DiMondo, Electrical Engineer

July 24, 2015    Newsroom

Arriving home after a long day of work, you might turn on the lights, put some dinner in the microwave, and put on the TV to watch that episode of your favorite show to help you unwind – pretty typical. Many people never come to the realization that all of these scenarios involve electricity. In fact, almost everything we do and take for granted requires electricity to function (even your car requires a battery). For many people, the mention of this word, or the words “voltage” and “current” are enough to send the brain into a state of either panic or indifference.

Electricity is that idea that your teacher tried to explain to your science class in high school for maybe a week or two, but somehow made everyone even more confused than they were before. The two things you may have gotten out of it: electricity is dangerous, and it’s magical (one of those things may be true) – it’s a concept that seems to betray our common sense at every turn. And that’s precisely why I made the decision to pursue Electrical Engineering in college – partially because of the challenge, and partially due to simple curiosity. I wanted to know more about this elusive force that controls literally every facet of our lives. What I learned is that when it’s broken down, the very basics of electricity can be surprisingly simple. I’d like to share some of this basic knowledge in the hopes that many of you will learn something new, and also that I might help spark some of your own curiosity into this magical subject.

First, the basics: Current (measured in amperes) measures movement of electric charge, or simply the flow of electrons in a wire or any conductor. Voltage (measured in volts) is a measurement of the difference in potential electrical energy between two points in a circuit – generally, it is between one point and a “ground,” or a reference point that is perpetually at 0 volts. However, we sometimes measure the difference between two separate “hot” wires. The majority of household appliances and receptacles function at a voltage of 120 volts (that is, the difference between the “hot” wire and the ground is 120 volts). In order to create a current, you need two things: a continuous path for electrons to flow (a circuit) and a voltage (potential energy) difference in the circuit. This can be easily seen in a drawing of a typical simple circuit:

There are several things to observe from the diagram: the battery creates a potential difference (or voltage) in the circuit. Note the continuous path for current to flow from the positive to negative terminal of the battery. This creates a flow of electrons in the circuit (strangely enough, the measure of current is always opposite the flow of electrons, from positive to negative – technically current measures the flow of POSITIVE charge). In this case, the light bulb can be seen as a resistance – it opposes the flow of current. There is a very simple linear relationship between current, voltage, and resistance in DC circuits. This is known as Ohm’s law: V = IR. In a DC circuit where any two of these quantities are known, the other can easily be calculated. The lower the resistance in a circuit, the more current will flow for any given voltage V. Copper wires are used in many circuits largely for this reason – it has an incredibly small resistance (1.68×10⁻⁸ ohms per meter of wire). On the other hand, the average resistance of the human body under dry conditions is roughly 100,000 ohms (quite large).

If currents as low as 30mA (0.03 A) can be lethal, what is the lowest lethal voltage for a person with resistance of 100,000 ohms? Disclaimer: human resistance can be as low as a few hundred ohms under certain conditions. DO NOT try this at home.

The last thing I’d like to mention is the concept of electrical power. In its most basic form, the power (in Watts) absorbed by an electrical load (i.e. light bulb, refrigerator, or any appliance which draws electrical power) is equal to Voltage (V) * Current (I). For example, a 60 Watt light bulb rated for 120 Volts will draw 0.5 Amps of current. The light bulb not only requires approximately 60 Watts to function properly, but also requires the voltage to be relatively constant at 120 volts. Input voltages which are too high or too low will cause the light bulb to function erratically or not at all, and in some cases can also damage or destroy the circuit.

In reality, a circuit can feed multiple lights and appliances. To determine the total power of any circuit, it’s as simple as adding up the power requirements of each load. For example, if your circuit contains a 60W light, 120W Computer, and a 180W fan, the total power draw on this circuit is (240 + 120 + 60) = 360W. If the nominal voltage is again 120 Volts, you can easily find the typical maximum current you’d find on this particular circuit. (360/120) = 3 Amps.

A circuit with 3 loads (or resistances). In a typical power circuit, theInput voltage would be higher, resistance lower, and current higher than seen in the figure. Note that larger loads = more current = lower resistances.

However, it is important to differentiate between the power absorbed by a load (which is useful) and incidental power lost before it reaches its destination. No conductor is perfect (even copper has resistance) and this resistance can add up and cause electrical power to be lost before its target destination, which is unwanted and something engineers try to limit as much as realistically possible. This power loss is calculated seemingly a little bit differently – P(Loss) = I^2*R. Although it may seem different, a quick look at Ohm’s law will tell you it’s exactly the same as above.

P = I*V

V = I*R

P = I*(IR)

This number should be as low as possible, and there are two simple ways to accomplish this – you can lower the resistance of the circuit (better conductors, decrease lengths of wire) and more importantly, lower the amount of current on the circuit (while keeping the same amount of power). This is precisely why large transmission lines have such high voltages (some are over 500 kV), and also one of the reasons why the grid uses Alternating Current as opposed to Direct Current – but perhaps I should leave that for another discussion.

It is my sincere hope that I’ve encouraged some of you to learn even more about this unique and interesting subject, and I’d love to answer any questions you might have. With a working knowledge, electricity can be a safe and powerful tool – even if some of it can still only be best described as magic.

– Daniel Camporese, Electrical Engineer

May 3, 2010    Newsroom

Over the last 25 years, engineers and architects have strayed from the core values of their professions and pursued policies that reduced their involvement in projects for the sake of maximizing profits. This shortsighted policy of withdrawing from the central role in projects has had a devastating effect, reducing the design professional ’s influence and creating the need for other entities such as construction managers (CMs) and owner’s representatives to emerge and fill the vacuum created by the retreating professionals. Due to the absence of the design professionals from the construction site, CM’s and owner’s reps have had to rely heavily on the input of contractors, who may not always understand the nuances of the design and who, at any rate, have a different objective; consequently, too often negating the value and benefits of the design.

In addition to the voluntary reduction in services, design professional’s acceptance of a trend to minimize the time required to develop design documents greatly increases the likelihood of errors and omissions. These, in turn, increase the construction cost extras, which further erodes the standing of the design professional and threatens the legitimacy of the profession itself.

Until now, the new project delivery systems, including design-build, have only had marginal success. Coupled with the owners’ continued dissatisfaction, this lack of success has today given rise to a whole new group of consultants and entities to try to meet the demands of the marketplace. LEED, Commissioning and Energy Services are all new growth areas that many firms have rushed to include in their scope of services. While this is a positive trend, unless there is a basic change in the philosophy of how these and all design services are provided, it will only be one more step in the market’s search for true value.

While we should and must strive to develop new and better solutions through the application of new technologies and methods, the lack of value to the client has been less affected by a reduction in innovation than by a lack of attention and follow-through. It is in this area that there exists the greatest opportunity for improvement and where Collado Engineering excels.

Al Collado, P.E., CEA