Just thought about it. If not, I'm sure they would be deaf by 30.
To give my usual caveat, I can't speak about blacksmiths, but I can speak about armourers. I haven't seen any indications that medieval armourers used hearing protection in the sources I have encountered. This isn't proof that they didn't do it, mind you, but given the utter lack of evidence I'd say it seems like they didn't. But what sort of evidence do we have? I am not aware of any instruction manuals or written books about the actual forging of metal from the middle ages, in terms of 'how to' guides like you see today, that would cover things like safety Equipment. We have sources like Theophilus and others that provide recipes and instructions and theoretical explanations (particularly, in the 16th century, we have De Re Metallica) but this is different from 'how to be an blacksmith/armourer/swordsmith'. We do have the afforementioned treatises, which are short on details, and we have illustrations of metal smiths of various types, and we have inventories of armourers tools. None of these seem to indicate that hearing protection was used. So now that we've touched briefly on the treatises, let's talk about the other sources.
As I said, have a number of illustrations of armourers and other smiths, from the 15th century on through the 16th and the early modern period. These illustrations span centuries, subjects (allegorical works, illustrations to poems, Hausbuchs assembled by guilds for their members) and are executed in a number of different artistic styles, from the stylized kind of visual shorthand of medieval manuscripts to early modern engravings that have all the appearances of 'realism'. Here are some examples, which can be found collected here*:
[Ulrich Lochner of Nuremberg, from a hausbuch showing tradesman, 1535](https://www.pinterest.com/pin/464715255285103913/
As you can see, none of these examples, or the others posted with them, show hearing protection. This is true of the somewhat stylized illumination and the more detailed engraving, and the watercolor illustration in the hausbuch, prepared to illustrate the tradesman themselves. But it's always important to look at visual sources critically. Did armourers workshops looks like they are depicted? Maybe not. Artists are concerned with things other than realism - showing faces for aesthetic reasons, composing an image in a pleasing way, using it to tell a story, and showing to inexpert readers what is going on. This might be the cause for the piles of tools and armour pieces strewn about in so many images (or maybe, armourers were just slobs). We can't simply look at these images, even a lot of them, and say with certainty, 'that's how it is'. But we can consider what they show, and they don't show hearing protection.
Similarly, in the inventories of the Greenwich Armouries from the 16th and 17th centuries list all manner or tools, but list no hearing protection. However, this might not mean as much as it seems, since the tools listed are the goods of the shop, not the armourers themselves - gloves, aprons, etc. are not mentioned, so we would not expect hearing protection to be listed.
So while we can't be definitive that armourers never wore hearing protection, there isn't any evidence that they did. While I am not an expert on later periods, in general concerns about hearing loss have increased over time, and with them, so have efforts to protect ears from repetitive loud sounds, even those not immediately deafening. Medieval armourers hammering away bare-eared would be in keeping with other trades which formerly operated without hearing protection.
Now, did this result in hearing loss? I have yet to see evidence that it did. We -do- see many accounts that armourers workshops (and those of other smiths) were indeed very loud places. Nicholas Dupras discusses this in his thesis:
The workshop must have been an extremely loud environment. The constant beat of hammers on hot and cold metal, the ringing of the anvils and stakes, and the blowing of the forge’s bellows must have combined into a riotous cacophony. As one fifteenth-century writer put it in his Complaint against Blacksmiths, ‘Dryue me to deth wyth den of here dyntes. / Swech noys on nyghtes ne herd men neuer: / What knauene cry, and clateryng of knockes!’152 Biringuccio, when describing the men who worked with iron, noted that ‘As you can understand, the unhappy workmen are never able to enjoy any quiet except in the evening when they are exhausted by the laborious and long day that began for them with the first crowing of the cock’.
But when it comes to this causing more lasting damage, I have not heard of any accounts of armourers complaining of hearing loss later in life. The main example I have of a disabled armourer is that of Fillipo Negroli, who became famous in the 1530's and 1540's for making armours like this that combined classical motifs with sheer fantasy. But toward the end of his life, in 1570 or so, he wrote of "having suffered for a long time from serious illnesses and being reduced to such great poverty ... because of the blindness that afflicts me."
But this isn't to say that armourers and other smiths didn't suffer from hearing loss, or other injuries as the result of workplace hazards (like tendonitis or other problems in the elbow and shoulder, one suspects). But like many other details of the daily life, work and health of common people, these details are hard to find in our records.
Sources:
Images as cited
Matthias Pfaffenbichler - Armourers
Nicholas Dupras - Armourers and Their Workshops: The Tools and Techniques of Late Medieval Armour Production
Phyrr et al - Heroic Armour of the Italian Renaissance
*As always visual sources are valuable inasmuch as we can understand them in context, and image boards like this are useful as long as we remember that, and become worrying when we decontextualize the image.
