Schnave

I’m a big fan of all natural but always happy to check out augmented engine sound.

The owner’s manual, when describing Sport and Sport+ Mode, makes vague reference to “Optimized engine sound in the vehicle interior”. So what is that? Just how is it optimized? Is it natural or is it augmented with audio trickery? In other words, is it Memorex or Milli Vanilli? This called for another deep-dive into the rabbit hole!

Sound is a large part of the Porsche driving experience. Early air-cooled Porsche engines generated a cacophony of valve train noise, cooling fans, and the unmistakable raspy bark of the flat-six exhaust. Glorious!

EU drive-by noise regulations signaled the end of the air-cooled engines. Additionally, consumer demand for quiet interior during highway cruising resulted in more and more soundproofing to further deaden any remaining engine sound. But what about those who want that sensory experience of that glorious engine for which they paid the big bucks?

Sport exhaust partially solved that problem. With valved exhaust, drivers could choose differing sound levels. That is, within EU sound regulation limitations. ☹️ That’s great if you have the windows down. Windows up; not so much.

Head acoustics engineer Dr. Bernhard Pfäfflin states that the Porsche engine sound is not artificially created; it’s authentic. “Artificially generating sounds and adding them to the drive spectrum through speakers is absolutely out of the question.” So how do they make cockpit noise louder without reducing soundproofing or using speakers?
https://www.porsche.com/usa/aboutpor...iew/article06/

Enter the Porsche Sound Symposer system. The Sound Symposer ducts existing *natural* air intake noise through sound tubes into the cockpit — just like a stethoscope. The system is valved similar to the Sport Exhaust system. Quiet on the highway and rowdy during sport driving. Awesome solution! 👍🏼 Here’s a diagram of the system installed on last gen’s Cayenne GTS:
https://www.excellence-mag.com/issue...-engine-sounds


But wait! The Sound Symposer is not installed on our 9Y0 Cayennes. How is the interior engine sound optimized? Remember how Dr. Pfäfflin stated Porsche would never use speakers to augment the sound? The truth depends on your definition of “speaker”.

Porsche installs Soundaktors in the 9Y0 Cayennes. Soundaktors have a horrible reputation with VAG enthusiasts, so Porsche won’t call them that. Instead, Porsche calls them “Actuator for Impact Sound”. Sorry, Porsche, but it has the same part number as the VAG Soundaktor: 4H0907601D. Busted.

This system uses a hockey-puck-size voice coil to vibrate the firewall and windshield; similar to a sound board in an upright piano. It is essentially a speaker that uses the firewall instead of a speaker cone to generate sound. VAG uses the same system in Golfs, Jettas, Beetles, and certain Audis. EDIT: Also installed in the Lamborghini Urus. Understandably, Porsche doesn’t really want to talk about this.
https://www.popularmechanics.com/car...roar-11291754/
https://en.wikipedia.org/wiki/Soundaktor


Next question. What is the source of the sound being produced by the speaker, er, Soundaktor? (Sorry. Porsche said they don’t use speakers.) In other VAG applications, the Soundaktor reportedly plays recorded sound files — MP3’s so to speak. Pretty cheesy, if you ask me. VAG denies this. Oh really? Page 20 of Audi’s self study program specifically addresses the sound files. It also calls the Soundaktor a speaker without a speaker cone.
https://www.audiclub.fi/audifinns/fi...tch?id=1628364


From what I can tell, Porsche installs a sort of microphone in the engine compartment. Porsche calls it “Loudspeaker, Engine Sound System.” Is the sound transmitted as it was captured, or is it augmented? I don’t know. Perhaps it is processed to eliminate road noise or other undesirable sounds. Regardless, that sound is converted to an electrical signal and played by the Soundaktor when in Sport and Sport+ mode. Other VAG applications allow drivers to modify the sound and adjust the volume. No such capability is available in the PCM.
https://www.caranddriver.com/feature...ned-tech-dept/

I think Porsche wants as little attention as possible with this system. It seems as though VAG bean counters are overruling Porsche sound engineers. No mention of it in any Porsche technical documents. I found it hiding in the parts diagrams. But they were awfully proud of the previous Sound Symposer system and published several documents expounding it’s virtues. Not a peep about the Soundaktor from a VW Beetle.

I’ve tested the system by switching between Sport, Sport+, and Normal while maintaining steady throttle and manual gear selection. It indeed augments the sound with a deeper note which is noticeable if you are listening for it. No difference between Sport and Sport+ though.

I’m a little disappointed that my Porsche uses the same engine sound system as a VW Beetle. Honestly, I would have preferred all natural. How about you?

signes

Was expecting different content from the title... either way definitely a fan of all natural. Lol

daveo4porsche

very interesting post thank you - I learned a lot - I’m wondering about what they’ve done on a Turbo S eHybrid - maybe this system is the source of all my CEL’s -

toma nova

I’m not a fan of fake noise. PSE, turbo whine, etc. are great when part of the actual driving.

My favorite engines noises have been full Magnaflow on a 2001 V8 Mustang, valve clatter on my air cooled Moto Guzzi, and most recently, the surprisingly loud CAI on my Miata.

Schnave

^^^Yep. Mustangs have some good sound. Big blocks from the late 60’s are also a favorite.

My very favorite is the BRM V16 engine. Sounds like a howling demon that just escaped from hell.

Be sure to check out the drive-by’s at 2:00 and 3:40. At 6:00, they move the microphone the cockpit and drive another lap. I play it on my home theater and turn it up to 11. Pure ear ****. No need for blue pills; just listen to this. 😜

Silververtu

Thanks for the post!!! I didn’t expect Porsche would use artificial sound on their products (except Taycan, no one wants to hear washing machine in spin cycle).

With all the noise insulation, i wonder if PSE also uses artificial sound inside the cabin. I had this thought flashed in my mind when I test drove a Panamera 4S with PSE. The exhaust sound was very pronounce in a very quiet cabin.

kayjh

I'm not a fan of artificial noise and prefer to hear natural sounds as long as they are pleasant. I had a 2017 991.2 with PSE. That exhaust had an annoying drone that I found hard to get used to. Porsche also piped induction sound into the rear of the cabin though a "sono tube" connected to the package tray at the back of the car. I had it disconnected, which helped a bit, but not much. I wonder what else was back there being piped in? It bugged me so much I got rid of the car.

Best natural sounds? Earlier Boxster with flat 6. Those engines made the coolest wing sounds and other mechanical sounds as they wound up. I preferred listening to them as compared to exhaust sound (PSE or not).

To each his own, I guess.

CanuckGT4

Can probably disable using software, will look into this.

Schnave

Might be easier to electrically disconnect it by pulling the plug. Google “disconnect soundaktor” and you’ll get over 1,300 results. Most folks don’t like their engines lying to them.

CanuckGT4

Then you'll have error codes being thrown which is not ideal.

Schnave

I hadn’t thought of that — good point! I won’t be disconnecting mine, though. While I’m disappointed that Porsche is using a Soundaktor, the implementation isn’t too bad. The sound during my tests was deeper and actually sounded fine. I think Porsche is using some portion of actual engine sound rather than being totally bullied by VAG and playing sound files. At least, that’s what I’m telling myself. 😎

EDIT: Congratulations on your new GTS! That is a fine looking ride. I’m kind of partial to Quartzite Grey with yellow calipers!

ace37

If so the resolution to that may be as simple as to measure the electrical resistance of the speaker and then replace the speaker with the appropriate $0.50 resistor. It typically works for airbags.

They could have gone super fancy and looked at impedance across a spectrum of frequencies but I’d be surprised if they found a good reason to bother. Only if the engineering intern was super bored.

ludey

Very interesting! They use similar, albeit simplified, technology in movie theater (and home theater) seating. You can even buy the unit separately, check it out: SoundShaker Different application but the principle is the same.

I read up on this a bit in the past when I went down a rabbit hole related to the same "engine sound augmentation" in my M4. Turns out the sound itself was not anything like a pre-recorded mp3... it's actually synthesized. And based on the engineering in the diagrams you shared, I'm pretty sure that's what is happening here as well. The biggest clue is that the information of which vehicle, engine equipped, engine RPM, load, etc is fed to the unit via the CAN data bus. This information, combined with the characteristics of the system itself (e.g. it's location and desired effect) are used to synthesize the "media stream" which is played. There is no doubt a lot more to it; quite a bit of sound engineering goes into these systems.

While I'm very interested by the engineering of this system, it makes you stop and realize that a not-insignificant cost is added to our vehicles for something I have yet to find anyone who prefers it.

Thanks for sharing!

XLR82XS

Can always close the circuit via paper clip.

CanuckGT4

Yeah, that would never cause any problems