Until Sparklings are adjusted to compassionate parenting, they often are only heard making noises of complaint or defensiveness. However it has been recorded that some sparklings will form groups and they'll have their own little trills, whistles, honks, and beeps that mean different things. When they are more accustomed to a gentle parent they make a great deal more noise.
There's many many noises a sparkling will make with a wide range of meanings. And depending on their development the same sounds might sound different between sparklings. Here are just a few:
One noise that I like to think Hissy Sparklings make is similar to baby Alligators: LINK. Little pew pew noises. That's often a noise of agreement or acknowledgement. When used in repitition it means the sparkling is trying to grab someone's attention.
They'll make little Boo-oop? Voo-eep! noises to greet someone they like or express excitement.
When they feel safe and relaxed their little engines purr. Imagine a high pitched car engine rumble.
A loud grinding noise is often the precursor to an angry sparkling tantrum.
They'll often sound off a honk noise when they urgently want someone's attention. Aggressive repetitive honking is usually a sparkling being obstinate or throwing a tantrum. One single LOUD honk usually is a big "no!". Often heard as a defensive warning if you approach a feral sparkling too fast.
They are sometimes heard making a whistling noise to themselves when they feel content.
They are also little parrots at times. They'll imitate noises or words they hear similar to human children. The only difference is their ability to mimic is uncanny and often turns into shenanigans. Many a Cybertronian parent with a filthy mouth has been outed by a sparkling repeating a swear word over and over.
Sometimes sibling sparklings will annoy eachother with repetitive beeping, screeching, or honking
Many sparklings make a little mechanical trickling noise when they are thinking or focused. Similar to human tutting or humming.
Happy trills are very common when a sparkling feels happy and safe around a person.
Special Vocal Abilities
Some sparklings are created or develop enhanced vocal abilities naturally. Jazz was a good example of this, he is capable of basically being a one man acapella group and can talk or sing different notes at the same time in multiples of his own voice.
Soundwave and Bumblebee both developed an ability to naturally record and replay the noises in the world around them. A lot of Cybertronians can gain the ability to do similar things due to later life augmentations but it can happen naturally.
Some sparklings learn and develop a noise that is so high pitched that it is painful to the ear as a defense mechanism. These sparklings often will later use these ear piercing ringing noise as a way to throw a tantrum and get what they want. Some create this noise through their vocal processor and others develop it through somewhere else in their body like a siren.
Pre-war caregivers assigned to educate and raise the Medic caste had specific training for this ability since a siren noise was something they often did their best to force a young sparkling to develop for their assigned future career. Ratchet will never admit it but he was a rarer sparkling who developed his siren naturally at an even higher pitch than "desired" at a very young age so he would often harass his assigned caregivers with it.
Side note that I'll talk about more later but with regards to the Hissy Sparklings, they arent born inherently mean or aggressive.
They do come out built for self defense but the actual Hissy part comes from having to survive the labyrinth as well as the treatment of pre-war sparklings. Think of feral kittens. Kitties arent born mean but they learn to hiss and bite to survive. Some sparklings even form little packs and are very affectionate with eachother.
Okay so i didnt make it a part of my official comm sheet BUT I am offering
*A character of your choosing as a hissy sparkling. Can be canon or OC*
as an option. They'd be sketches similar to the other hissy babies sketches i've done (it'll be sketchy but a little cleaner than those) and be $15 dollars
I'll make a prettier looking sheet about it but know that these mini comms are open and theres 5 slots.
So... what I can gather from Transformers: Exodus... is that all new sparks from the Allspark basically have to survive through a hellish environment while climbing up to the surface.
So consider...needing to survive through so much at the start of their life, generally, cybertronian sparklings are actually vicious, dangerous little things with developed claws, teeth, and other defences.
I've been thinking about this for a long time now and this finally gives me support to have a good enough excuse to yell about my thoughts. SO I'm gonna take that small bit and run with it in my general versions of canon.
Sidenote: I wanna establish before I go deeper into this headcanon that this behaviour is not frame-type exclusive. The aggressive babies would be, across the board, all cybertronians. It's a species thing, not exclusive to any subgroup of cybertronian.
Sparklings aren't helpless like a lot of young species are (like humans where babies can be injured just by looking at them wrong snjxwj) but instead are more similar to how a foal can walk shortly after birth or how a T. Rex grows from a lanky speedy little thing till it's big enough to be a big chonker and not need the same defense mechanisms anymore. (Check out this illustration by RJ Palmer to see what I mean.)
Consider.... during the rebuilding of Cybertron post-war many Cybertronians wanted to raise/adopt newsparks. But instead of the cute experience you'd expect when picking out a sparkling to raise, it's more like trying to coax out a feral cat. Before a regulated system to help young cybertronians can be formed, they can also rise at different levels of development. A few are even near adulthood by the time they emerge since the climb is heavily dependent on each individual spark and luck since it's very easy to become lost for long periods of time. On the flipside, lucky keeners who are good survivors could be very very young and small when they emerge. Most are somewhere in between. The age would also affect the role a caregiver would provide.
Cut to cybertronians on a new cybertron attempting to herd these small little hissing hell demons. Mechs covered in scratches and not caring one bit because they finally managed to coax out the little car who had backed itself into a small hole and had been aggressively beeping and honking at them. Mech's trying to pry off a smol cybertronian that is gripping their helmet with it's little teeth and them taking it in stride with a "I think this one likes me!"
And yes I already hear the debate starting about how cybertronians should or shouldn't emerge in their full sized armor. For the sake of this post I'm going with them growing into their armor and even some of their armor development having adaptive growing that's dependent on what they go through. I could talk about this for hours and I hope to make a more in depth post about cybertronian development but I can be forgetful so if you wanna hear more feel free to remind me djjdsjz.
In the new world after the war, wanting to adopt and raise a sparkling isn't uncommon of cybertronians and during rebuilding efforts, many search different levels from the well for young ones. Ideally a cybertronian taking on a big role in a newspark's life would have a compassionate and patient demeanor and encourage the sparkling to grow it's own way. Eventually there could be stations setup as close to the well of sparks as possible that either transport, or aid in their journey to the surface and furthermore aid in matching temperaments of newsparks and adopters
Cybertronians end up yoinking the human term/idea of family but making it more about a group of individuals who care deeply about one another. Basically, family becomes about who you love, regardless of what type of love it is. They don't view family the way humans do. Familial social constructs and dynamics wouldn't apply. Romantically paired cybertronians aka Conjunxes are just one type of 'parent' and not a standard or even a majority. Many newsparks would be raised by one 'parent' or a pair of amica enduras. Some end up being raised by a group of cybertronians who are so close they consider eachother family.
Brief Sparkling History
Before the war I imagine they had setup stations below the surface to catch sparklings and essentially label them straight away by their frames into a caste and job. By catching them early they could also influence and even straight up modify their armor and protoform development to be ideal for their assigned position.
But nearing the time of the war, when the caste system was at its peak, there had been very few sparklings emerging from the well at all, so most collection stations were abandoned and eventually destroyed from the combination of lack of upkeep + harsh conditions.
Without many checkpoints or mechs braving the depths to search for the little tykes, a fair number of those who emerged from the well right before and during the war end up fully grown on their own whether from having to survive on their own on the surface, or having to navigate the depths for so long the old fashioned way.
Bumblebee is one such case who'd essentially been the equivalent of barely an adult when he'd been swept up by autobots. At this time he was on the younger side of newsparks without guidance emerging from the well. Bee, though young and small, had seemingly come out of nowhere to scare off some decepticons who were terrorising an Autobot minicon. He didn't know the minicon was a spy with incredibly important information for the autobots before acting, he just acted in a situation he felt was unfair. He also was unaware that he'd had an audience in the form of a rescue team headed by an incredibly impressed Optimus with a concerned Ratchet in tow. Optimus and Ratchet, both too charmed by Bee to do otherwise, end up accidentally falling into the role of semi-parental mentors.