Why do people often say 'hambag' for 'handbag'?

Edit

The comments here are full of disbelievers!

"I've never heard handbag pronounced that way. Which country are you from?"

Oh ye of little faith! So - I've attached a couple of examples here from that video site place. Watch the first from 23 seconds in. There's about five or six 'hambags' in the next half a minute: Hambag. Here's a second one, an American English speaker this time. He also says it about 23 seconds in too: A bag for sweet hams. Lastly, here's an altogether different pronunciation which you may find rather interesting. It's by far the best: A handbag?

The question

It's all in the title really. The other day I was hanging out with some teachers. They were all talking about /hæmbægz / i.e. 'hambags'. Ever since then I've been hearing people do this all the time. What's with the bags for ham?

What are the restrictions there on dropping one of the letters. I mean I can't say 'bangroll' /bæŋrəʊl*/ for bankroll. And I can't drop the /d/ in 'bedroom' and say /berʊm*/. Why can I drop a /d/ in 'handbag' when I can't drop a /k/ in 'bankroll'?

Secondly, what's happening to the /n/ there? Is it changing? If so why? After all we can't change the /m/ for example in 'hemlock' to 'henlock', although that would be much easier to say.

What's with the ham?

This is a simple case of cluster reduction of /db/ → /b/, combined with assimilation: /n/ is labialised to /m/ before a bilabial consonant /b/ or /p/, and velarised to /ŋ/ before a velar consonant /g/ or /k/.

I expect the cluster is reduced because it’s relatively uncommon. This is often where you encounter reduction and epenthesis. Compare:

nuclear /klj/ → nucular /kjʊl/
hamster /mst/ → hampster /mpst/

I’m a native speaker of American English, from New England, and a good portion of the time in running speech, I pronounce the cluster /db/ as /bː/ or /b/:

goodbye (goobbye)
birdbath (birbbath)
bedbug (bebbug)
deadbolt (debbolt)

And the cluster /ndb/ as /mb/:

windbag (wimbag)
sandbox (sambox)
windburn (wimburn)

English has a long history of cluster reductions involving nasals and stops:

/kn/ → /n/ in “knight”
/gn/ → /n/ in “gnome”
/mb/ → /m/ in “lamb”

So I expect this is little different.

Having mulled over this a bit, I have come to the following conclusion(s). I should note that I have no sources and am aware of no prior research to back up my claims; but I hope they bear themselves out.

There are two levels of sound change at play here, as others have said: cluster reduction and nasal assimilation.

[Note: For the sake of simplicity, I ignore dialectal variation and use generic, simplified RP for my IPA, excepting the non-RP pronunciation of some clusters.]

Cluster reduction in compounds and sandhi

First, the cluster /nd/ in handbag is reduced to just /n/. Whether a word-final /nd/ cluster is or can be reduced depends on a few things.

Morpheme boundaries

If there is a morpheme boundary between the /n/ and the /d/, the ability to reduce the cluster is significantly reduced. Thus the past tense forms penned and mined are not usually reduced in any context, even before a stop (see below).

On the other hand, if there is no morpheme boundary between the /nd/ cluster and the following element (i.e., the /nd/ is not word-final), then the ability to reduce is significantly increased. There are only a few words where non-final /nd/ is followed by anything other than a separate morpheme (like finder with the morpheme -er), but one such word is sandwich, in which /nd/ is indeed usually reduced—albeit sometimes quite irregularly to an [m], which to me makes no sense whatsoever and must be regarded as spurious and unpredictable.

Quality of preceding element

If /nd/ occurs after a phonemically long vowel or a diphthong, the ability to reduce the cluster is significantly increased. Thus mind, blind, and found can both be optionally reduced in any context, even at the end of an utterance.

If the /nd/ cluster ends an unstressed syllable, particularly one with a reduced vowel (usually [ə] or [ɪ/ɨ]), the ability to reduce the cluster is likewise increased, so that second or errand can be optionally reduced in any context. Something like imagined is less likely to be reduced, because of the morpheme boundary.

Quality of the following element

If none of the two first triggers is present, so we’re dealing with a phonemically short vowel followed by a tautomorphemic /nd/, then the ability of a given /nd/ cluster to be reduced depends on the element that follows it.

Going through the alphabet and finding/making up word pairs where the first ends in /nd/, I find the following general principles apply:

/nd/ is fairly consistently reduced to /n/ before /b d g p t k tʃ ʤ/
handbag, blonde girl, mend cars, wind chime, etc. all with reduction
/nd/ can optionally (but quite commonly) be reduced to /n/ before /l r m n f s ʃ θ/
landfill [lan(d)fɪɫ], landline [lan(d)ɫaɪn], handsome [han(t)səm], friendship [fɹʷɛn(d)ʃɪp], windmill [wɪn(d)mɪɫ], grand theatre [ɡɹʷan(d) θiːətə], handwriting [han(d)rʷaɪtɪŋ]
/nd/ is usually not reduced before vowels and /j w h v z (ʒ)/
handover [handəʊvə], grandeur [ɡɹʷandjʊə/ɡɹʷanʤʊə])

(There are some exceptions to 1. above, such as where proper names are involved: /nd/ is usually reduced in blind girl, but never (?) in Bond girl; and the generic noun sandwich is often reduced, as per above, but the place name Sandwich is usually not. Similarly, ad-hoc or uncommon compoundings are less likely to suffer reduction: landline is quite commonly reduced, but wandlore much less so. There are probably other exceptions, too.)

In other words, the reduction is:

ubiquitous before stops (including affricates)
optional (but common) before non-vocoid sonorants and unvoiced fricatives
possible (but less common) before vocoid sonorants and voiced fricatives (including /h/)

This seems to more or less follow a principle of sonority: the more sonorant the following consonant is, the more likely it is to block the reduction of /nd/ to /n/. /h/ is the exception here, but it is quite common for /h/ to be voiced [ɦ] in many positions in English, and it is typologically also quite common for /h/ to pair with consonants of high sonority.

If either of the first two triggers mentioned above is present, the following element still plays a role, but the overall ability to reduce the cluster is reduced or increased relatively. So mind can be reduced even before vocoid sonorants and voiced fricatives quite readily, but it is even more likely (almost certain, even) to be reduced before a stop; whereas mined does have the possibility of being reduced before a stop, but it’s far less likely—and before vocoid sonorants and voiced fricatives, I would say that reduction would be almost entirely absent and impossible.

Parallel clusters

Let’s compare this cluster with some similar ones. /nd/ consists of a nasal (which I’ll indicate as an archephoneme as /ɴ/) followed by a voiced stop, so similar clusters are:

/ɴ/ + /b/ => ‹mb›
/ɴ/ + /g/ => ‹ng›

Both these clusters appear on the surface with two different pronunciations: [m] and [mb] for /ɴb/, and [ŋ] and [ŋɡ] for /ɴg/. These alternations historically came some time during the first century of Modern English (around 1600 or so), as a result of ng-coalescence and mb-coalescence, which reduced them in word-final position, but not word-internally. Note that all the cases we’re discussing here, including handbag, are word-final, they are just frequently compounds.

Whereas mb-coalescence took place in all of English, ng-coalescence skipped a few dialects. In such dialects, song and singer are [sɔŋɡ] and [sɪŋɡə], but a songbook is not [*sɔŋɡbʊk], but [sɔŋbʊk]. A songwriter is often, but not always, a [sɔŋɡɹʷaɪtə]. Without being any kind of expert on these dialects, my hypothesis would be that the same general sonority principle as unearthed above is at play, and /ng/ thus matches /nd/ quite nicely.

That basically leaves us with a description of an ongoing historical change of word-final clusters, frozen in different ‘stages’:

Productive reduction common to all of the Anglosphere
= /nd/ gets reduced according to a sonority principle
Reduction still productive in some places, no longer productive in other places
= /ng/ split in twain, matching productive /nd/ in some dialects, but non-productive /mb/ in most
Reduction no longer productive, generalised the same way everywhere
= /mb/ always reduced everywhere

Nasal assimilation

Compared to all that waffle above, this should be quite simple.

English has three nasal phonemes /n m ŋ/, and (at least) four nasal surface phones [n m ŋ ɱ], the latter being a labiodental nasal. In other words, there are three phones that have a direct phonemic correspondent, and one that does not.

There are two types of nasal assimilation to consider here:

Full assimilation, which assimilates to any nasal phone.
Partial assimilation, which assimilates only to non-phonemic phones but cannot assimilate to a different phoneme.

There is, as far as I know, no real reason why the distribution should be the way it is in English, but it is as follows:

/n/ can undergo full assimilation: it can become [m ŋ ɱ]
/m/ can undergo partial assimilation: it can only become [ɱ]
/ŋ/ does not assimilate

Note that even in full assimilation, assimilation to a following nasal is much less common and mandatory than assimilation to a following stop or fricative. In practice—since /m/ can only undergo partial assimilation and /ŋ/ cannot occur syllable-initially—this means that /nm/ tends not to be assimilated to [mm] nearly as much as /np/ is assimilated to [mp], for example. Something like one more can be assimilated as [ˈwʌmˈmɔː] (possibly because of the stress distribution), but gunman is not likely to be assimilated as [ˈɡʌmːən].

Of course, in handbag, the reduction of /nd/ to /n/ has already taken place at a deeper level, and the highly productive and very near-surface process of nasal assimilation to a following stop occurs almost mandatorily in all contexts.

This means that the relevant phonemic input here is /hanbag/, which is then quite regularly (fully) assimilated to [hambaˑɡ].

There are two processes at work here:

Alveolar elision.
Alveolar assimilation.

Just behind your upper teeth - you can feel it with your tongue - there is a little shelf-like part of your mouth. It slopes slightly upwards. Behind that your mouth suddenly arches upwards to form the roof of your mouth. That shelf-like part you can feel there behind your teeth is called your alveolar ridge. In English, we make the following consonant sounds there:

/ t, d, n, l, s, z /

[Those last two sounds, /s/ and /z/, are a bit different. We don't touch central bit of the tip of the tongue against the ridge with these. Instead, (- there's a kind of line or seam that runs down the centre of the tongue there called the mid-sagittal line), we create a furrow along the mid-saggital line and the edges of our tongue rest against that shelf as air whistles down the channel in the middle.]

Anyhow, those sounds that we make on the alveolar ridge are very unstable in English. They very often disappear or they change dramatically according to the other sounds that they are next to.

Of all of these sounds, /t/ and /d/, the alveolar plosives (these consonants are like mini ex-plosions) are the most unstable, closely followed by /n/.

Alveolar plosive elision

As a rule, when the sound /t/ or /d/ occurs at the end of a syllable, it is liable to deletion whenever the following two conditions are met:

It is surrounded by consonants (not including /r/ or /h/).
The preceding consonant has the same voicing. (It must be unvoiced for /t/).

This means we can drop the /t/ in left work, because /f/ like /t/ is voiceless (there's no buzzing of the vocal folds). We can't drop the /t/ in halt work though, because the /l/ there is voiced.

This context will allow for /t/ or /d/ elision in nearly all cases in Gen Am and SSB English. However there are many other instances where /d/ or /t/ may be also be elided. For example, /t/ is freely omissible in normal speech in contractions with not - regardless of whether followed by a vowel:

aɪ 'kɑ:n 'ɑ:nsə [I can't answer - Southern Standard British English]
aɪ 'kæn 'ænsɚ [I can't answer - General American]

Alveolar assimilation

The consonants /t/, /d/ and /n/ are always liable to change according to the sound that follows. They remain the same type of consonant - /t/ and /d/ remain plosive and /n/ remains nasal - but they change their place of articulation. In front of bilabials - sounds made with the lips, namely /p, b, m, w/ - they become bilabial. In front of velar sounds /k, g/ they become velar.

For /n/ this means it becomes an /m/ in front of bilabials and /ŋ/ in front of velars:

im person, im bed, im my house, woman im white
ing Cambridge, ing Greece

This is never compulsory, but will happen the vast majority of the time for most speakers.

Handbag to Hambag

Here we see the alveolar elision of /d/. It is likely to disappear because it occurs at the end of the syllable hand, and is surrounded by the voiced consonants /n, b/.

That leaves us with /hænbæg/. The /n/ there is now going to be subject to alveolar assimilation: it is now liable to change to /m/ under the influence of the following bilabial, /b/: /hæmbæg/

Some further examples of alveolar assimilation

Hop pants
Whipebait
Hopmail
Heab porter
Birb bath
Goob morning
Imput
Im brief
Im my opinion
Am why exactly?
Hopmaildok-kom
lighk green
Goog karma
Deag give away
Easterng Kenya
Wimbledong Common
Womangkind

As already observed in the posts above it is a tendency in English - and other languages as well - to simplyfy certain groups of three consonants. In some words such as to listen /lisn/ the t between s and n is regularly not spoken and this is the standard pronunciation. In other cases such simplifications as /ˈhæmbæg/ are negligent colloquial style. I would not imitate it, especially if English is not your mother tongue as it shows that one does not care for clear and good articulation. It is not necessary to imitate every manner of speaking you hear. You should find your own style.