Sennheiser HSP 2 omnidirectional headset microphone review (for linguists)

If you have read any of my other reviews on this site, you may have noticed that the The Sennheiser HSP 2 is one of the three microphones that I typically recommend for the most demanding field recordings of speech for analysis and analysis/re-synthesis purposes. The other two are Beyerdynamic Opus 55 MkII and Shure Beta 53. If you don't feel like reading the rest of the interview, I will give you the one-sentence-long conclusion: the Sennheiser HSP 2 is a fantastic, though rather pricey, microphone. I do encourage you to read the rest of the review to see if the microphone is right for you.

Why this type of microphone?

Before I go into the details of the HSP 2 design and performance, I would like to explain briefly why this type of microphone is suitable for the most demanding fieldwork recording applications. First of all, it allows you to record a very flat and spectrally-neutral signal. Also, such microphones have a very broad frequency response, especially at the low end, and are resistant to popping. They are also resistant to proximity effect. They are small and allow for close placement. They are resistant to moisture, dust, and temperature. They are very small and lightweight. They are durable. They can be used in wireless or wired configurations. With the proper adapter (supplied with the mic), they can be interfaced with any professional pre-amplifier with phantom power. The HSP 2 meets this definition perfectly well.

Figure 1. The Sennheiser HSP 2 microphone, the MZA 900P phantom power adapter, and the padded plastic case

Design and construction

The microphone is a sub-miniature omnidirectional microphone, attached to a wire boom, which is attached to a behind-the-ears headband (or "neckband" as Beyerdynamic calls it). The microphone cable is terminated with the Sennheiser proprietary 3.5mm locking connector, which protects the cable from being accidentally disconnected from an input device. The microphone is designed to work with the Sennheiser system of wireless microphone technologies, but it comes with a phantom power adapter (see Figure 1 and Figure 2) that allows the microphone to be connected directly to a phantom-powered pre-amplifier (MZA 900P). Sennheiser USA sent me both the microphone and the adapter for review.

Figure 2. The Sennheiser HSP 2 microphone and the MZA 900P phantom power adapter

The build quality is excellent. The headband and the boom are not as sturdy as the Beyerdynamic Opus 55 MKII or the Shure Beta 53, but they are smaller and lighter, which makes them perfect for inconspicuous stage use. The boom can be detached from the headband, which is very useful if you want to mount the microphone on a different headset. I do this routinely because I don't like the behind-the-ear headbands, and neither do my interviewees, most of the time. This microphone is bound to last a very long time and give you thousands of hours of reliable use. It folds down to a very small, flat bundle, and can be stored easily in the supplied padded plastic case (Figure 1). The case is not as well-built as Pelican cases, but it will suffice, unless you decide to step on it or throw it in the lake. The technical specifications are summarized in Table 1.

Table 1. Technical specifications of the Sennheiser HSP 2 microphone

Acoustic characteristics

The Sennheiser HSP 2 has an omnidirectional polar pattern and a very broad and flat frequency response. These characteristics help obtain very clean, unaltered, and faithful recordings of speech. With proper placement, the microphone will give you fantastic spectral detail and very low noise. The microphone has a medium-low sensitivity, a little lower than the Shure Beta 53, but with lower self-noise (more about this later). The microphone is resistant to overloading (max SLP of 150 dB), which is perhaps less of a concern for speech recording, but it does help in some situations. Figure 3 shows a frequency response graph (according to the manufacturer). We can see a flat response in most of the areas relevant to speech, with an extended low-end. This microphone is perfect for recording speech for the analysis of low-frequency features, such as voicing, nasalization, spectral tilt, etc.

Figure 3. Sennheiser HSP 2 frequency response (according to the manufacturer)

In use

In everyday use, the microphone is excellent. The headband is surprisingly easy to use, and, most importantly, retains its settings, so the microphone always ends up at the right spot. I don't particularly care for this type of design, but I do use my own headband with these types of microphones. Because the boom is detachable, the HSP 2 can be mounted on a more appropriate headband. Figure 4 shows my own headband. It works really well for me and my interviewees. It allows for easy and predictable placement, and is comfortable to wear, even for people with facial hair and big hairdos. I make a few different types of headbands; if you're interested in one, please, send me an email.

Figure 4. A more comfortable headband as a replacement for the behind-the-ears neckband. I use it with the Beyerdynamic Opus 55 Mk II, YPA, and Shure Beta 53.

Battery power

The Sennheiser HSP 2 is a professional microphone and so it complies with the professional phantom-power standard. However, this means that you will have to have a recorder or pre-amplifier that can supply phantom power. The problem is, of course, that not all field recorders supply phantom power, and few do it well. Therefore, it is often desirable to have a battery-powered microphone. The Shure Beta 53 does not have a battery-powered option any more, but you can use the Shure RPM626 belt-pack module (sadly, discontinued) with it. The Beyerdynamic Opus 55 Mk II can use a dedicated battery adapter (CV3), but there does not seem to be a similar option available for the HSP 2. However, you can use the Tram battery module (Tram TR-79+), which is designed for use with the Sennheiser EW wireless system. I haven't tried it, so I encourage you to check with both Tram and Sennheiser before you buy it.

Audio tests

Self-noise

The Sennheiser HSP 2 has very respectably low self-noise. It is almost as good as the Beyerdynamic Opus 55 MkII (at equivalent signal level settings), which is surprising, given the microphone's lower sensitivity, thus requiring higher pre-amplifier gain. The FFT in Figure 4 shows a slight bump in the low frequencies, which is simply some low-frequency rumble present in any urban recording environment, however quiet it might be. This is not the microphone's fault, of course.

Figure 4. Sennheiser HSP 2; FFT of self noise at the signal level of -12 dBFS, in a quiet room.

Spectral detail

With proper placement (read more about mic placement here), one can capture extraordinarily detailed recordings of speech. Such recordings are perfect for speech synthesis purposes. If you would like to use Akustyk to do speech synthesis, the microphone will make your job a lot easier. The LPC of the Polish vowel /a/ in the word "czarna" ('black'), shows very well-defined formant peaks, with narrow bandwidths and a very natural envelope (Figure 5). Similarly, the spectrogram in Figure 6 shows really rich, luscious detail. If there's such a thing as a work-of-art spectrogram, this one comes close. I would trust such recordings even for the most critical analysis. They are as good as the recordings obtained with the Beyerdynamic Opus 55 MkII and Shure Beta 53.

Figure 5. LPC of the Polish vowel /a/ in the word "czarna" ('black')

Figure 6. Spectrogram of the Polish phrase "czarna krowa" ('black cow')

Low frequencies

Low frequencies are the Achilles' heel of most commercially available microphones. However, the Sennheiser HSP 2 is able to capture a very natural spectral envelope even at the lowest frequencies. The FFT of the vowel /o/ in the Polish word "krowa" ('cow') shows a very natural envelope indeed, with excellent detail (Figure 7). I am confident that such recordings would give me accurate readings of nasalization and other measurements of speech that are particularly demanding of low-frequency detail.

Figure 6. FFT of the vowel /o/ in the Polish word "krowa" ('cow')

Conclusion

The obvious question is whether or not you should buy this microphone. If you have the funds, you should definitely consider buying it. The performance is unquestionably good. Your decision should probably be motivated by availability, warrantly, and technical support in your country. Sennheiser has a great worldwide presence. In the USA, the tech support has been great, in my experience. My favorite technical support still remains Nady, a small American pro audio company. Sennheiser is huge, which can be detrimental to getting good support. You have to be on hold for a long time, go through multi-level menus before you speak to a human being, and go through additional hoops before you speak to a knowdledgable human being. You do get good support, it just is not as easy as one might wish. In the case of Nady or Sound Devices, you get to speak to an actual engineer, who will patiently take your call, explain things in detail, and be helpful and efficient.

If your budget is limited, i.e., if you don't have a substantial grant for equipment, you should get really decent results with the YPA or the RadioShack microphones reviewed on this site.

Download original files

	Description	Quality	Comments
	Sennheiser HSP 2 with Sound Devices USBPre	48,000 Hz; 24-bit; mono	In a quiet room, calibrated at -12 dBFS