I want to speak about an application in Windows which helps ESL students in listening and spelling.
In this paper we present a tool that is aimed to improve the sound-to-letter skill of ESL students.
In the sentence above I want to emphasize that is a computer application, can I say computer tool? what is the best word
In your sentence, "software" or "software tool" would sound better than "computer tool".
I assume that this context is the introduction to an academic paper. In this context, there are several possible meanings of "tool", including software, a paper-and-pencil evaluation tool, or even a mirror. As Will points out, "computer tool" is not idiomatic. Also, the phrase "aimed to" is not idiomatic. The word "software" means "computer program(s)", and can include anything from small pieces of a program to collections of many programs.
In your professional jargon, is "sound-to-letter skill" a singular noun that includes the skill of converting all sounds to letters? Or did you mean to use the plural "sound-to-letter skills", which treats transcriptions of different sounds as distinct skills?
I would change the sentence to something like one of these sentences:
In this paper, we present software that is designed to improve the sound-to-letter skills of ESL students.
In this paper, we present software that is intended to improve the sound-to-letter skills of ESL students.
In this paper, we present software that is aimed at improving the sound-to-letter skills of ESL students.
It depends on your audience - if they have a little bit of IT knowledge, they will definitely know that you mean a kind of computer application (especially in context), instead of a hammer or screwdriver.
Adding the word 'computer' does not make it any clearer - a screwdriver could be a 'computer tool' as well because you need one to open it up. If you're unsure, use 'computer program': everybody will know what you mean by that.
As a developer, I am constantly second guessing myself as to what to call certain kinds of programs.
I would call a language-teaching program a "tool". Tool implies a certain usefulness that is not implied by "software" or "application." Facebook or video games can be called software. A teaching software can confidently be called "tool." Note that while "computer software" is acceptable, "computer tool" sounds odd.
An opinion-based hierarchy for terms:
Software - does the most, could have dozens of uses (Like an operating system)
Application - Generally does one thing, sometimes more but generally related to the same task (clock that also is a timer and stopwatch.)
Tool - Is focused on one task (A web-browser or language-teaching tool)
These are just my opinions, hope it helps.
