Why is 一歩 pronouced 'ippo'?


I am very new to Japanese, but I noticed this today.

In Wiktionary article on 一歩 we see that the pronunciation is いっぽ. In article
for 一 we see that there is a nanori reading いっ. On the other hand in the
article for 歩 we see that only sensible reading here would be ほ. But put
together we get いっぽ. Also in Wikipedia article for っ, it says that sokuon
won't appear before h, except in loanwords or nonstandard speech.

So, why there appears to be a っ before h here? And why does it appear to
transform the ほ to ぽ?




It's a simple matter of contraction.

一 is normally pronounced as いち (ichi), and 歩 can indeed be pronounced as ほ
(ho).

一 can also be pronounced as いつ, and whenever a kanji ending in ち or つ is
followed by は、へ、ひ、ほ or ふ, they contract and turn into っぱ、っぺ、っぴ、っぽ or っぷ.

Some more examples:

[code]

    八百 = はち + ひゃく → はっぴゃく
    失敗 = しつ + はい →　しっぱい
    一杯 = いつ + はい → いっぱい
    
[/code]

And so on, and so forth. The more you get in touch with Japanese, the more
natural it will become. Do note that this does not happen when the **h** is
naturally already a **b** , as e.g. in 発売 (はつばい).

It will also happen when the second kanji starts with either a **k** or a
**s** sound:

[code]

    一回 = いつ + かい → いっかい
    結婚 = けつ + こん → けっこん
    一緒 = いつ + しょ → いっしょ
    達成 = たつ + せい → たっせい
    
[/code]

To be clear: there are of course exceptions, but these are **far** fewer than
words following this rule.

**Edit**

Anyone care to explain the downvote? I don't mind being wrong, but I'd like to
know why.

